Kapitel 15

Question 1

Adjustment of sensitivity following repeated stimulation. The mechanism that allows a cell to react to small changes in stimuli even against a high background level of stimulation.

Answer 1

adaptation (desensitization)

Question 2

General term for a protein that functions solely to link two or more different proteins together in an intracellular signaling pathway or protein complex. (Figure 15–11)

Answer 2

adaptor protein - adaptor

Question 3

Membrane-bound enzyme that catalyzes the formation of cyclic AMP from ATP. An important component of some intracellular signaling pathways.

Answer 3

adenylyl cyclase (adenylate cyclase)

Question 4

Serine/threonine protein kinase that acts in the PI-3-kinase/Akt intracellular signaling pathway involved especially in signaling cells to grow and survive. Also called protein kinase B (PKB).

Answer 4

Akt

Question 5

Member of a family of proteins that contributes to GPCR desensitization by preventing the activated receptor from interacting with G proteins and serving as an adaptor to couple the receptor to clathrin-dependent endocytosis. (Figure 15–42)

Answer 5

arrestin

Question 6

Plant hormone - commonly indole-3-acetic acid - with numerous roles in plant growth and development.

Answer 6

auxin

Question 7

Multifunctional cytoplasmic protein involved in cadherin-mediated cell–cell adhesion - linking cadherins to the actin cytoskeleton. Can also act independently as a transcription regulatory protein. Has an important role in animal development as part of a Wnt signaling pathway.

Answer 7

beta-catenin (β-catenin)

Question 8

Class of steroid signal molecules in plants that regulate the growth and differentiation of plants throughout their life cycle via binding to a cell-surface receptor kinase to initiate a signaling cascade.

Answer 8

brassinosteroids

Question 9

Serine/threonine protein kinase that is activated by Ca2+/calmodulin. Indirectly mediates the effects of an increase in cytosolic Ca2+ by phosphorylating specific target proteins. (Figure 15–33)

Answer 9

Ca2+/calmodulin-dependent kinase (CaM-kinase)

Question 10

Ubiquitous intracellular Ca2+-binding protein that undergoes a large conformation change when it binds Ca2+ - allowing it to regulate the activity of many target proteins. In its activated (Ca2+-bound) form - it is called Ca2+/calmodulin. (Figure 15–33)

Answer 10

calmodulin

Question 11

Multifunctional Ca2+/calmodulin-dependent protein kinase that phosphorylates itself and various target proteins when activated. Found in most animal cells but is especially abundant at synapses in the brain - and is involved in some forms of synaptic plasticity in vertebrates. (Figure 15–34)

Answer 11

CaM-kinase II

Question 12

Member of the Rho family of monomeric GTPases that regulate the actin and microtubule cytoskeletons - cell-cycle progression - gene transcription - and membrane transport.

Answer 12

Cdc42

Question 13

Internal cyclical process that produces a particular change in a cell or organism with a period of around 24 hours - for example the sleep-wakefulness cycle in humans.

Answer 13

circadian clock

Question 14

Photoreceptor cell in the vertebrate retina that is responsible for color vision in bright light.

Answer 14

cone photoreceptor (cone)

Question 15

Form of intercellular signaling in which signal molecules remain bound to the surface of the signaling cell and influence only cells that contact it.

Answer 15

contact-dependent signaling

Question 16

Transcription regulator that recognizes the cyclic AMP response element (CRE) in the regulatory region of genes activated by cAMP. On activation by PKA - phosphorylated CREB recruits a transcriptional coactivator (CREB-binding protein; CBP) to stimulate transcription of target genes.

Answer 16

CRE-binding (CREB) protein

Question 17

Plant flavoprotein sensitive to blue light. Structurally related to blue-light-sensitive enzymes called photolyases (involved in the repair of ultraviolet-induced DNA damage) but do not have a role in DNA repair. Also found in animals - where they have an important role in circadian clocks.

Answer 17

cryptochrome

Question 18

Latent transcription regulator that mediates the effects of Hedgehog.

Answer 18

Cubitus interruptus (Ci)

Question 19

Nucleotide that is generated from ATP by adenylyl cyclase in response to various extracellular signals. It acts as a small intracellular signaling molecule - mainly by activating cAMP-dependent protein kinase (PKA). It is hydrolyzed to AMP by a phosphodiesterase. (Figure 15–25)

Answer 19

cyclic AMP (cAMP)

Question 20

Specific enzyme that rapidly and continuously destroys cyclic AMP - forming 5′-AMP. (Figure 15–25).

Answer 20

cyclic AMP phosphodiesterase

Question 21

Enzyme that phosphorylates target proteins in response to a rise in intracellular cyclic AMP. (Figure 15–26)

Answer 21

cyclic AMP-dependent protein kinase (protein kinase A - PKA)

Question 22

Nucleotide that is generated from GTP by guanylyl cyclase in response to various extracellular signals.

Answer 22

cyclic GMP (cGMP)

Question 23

Specific enzyme that rapidly hydrolyzes and degrades cyclic GMP.

Answer 23

cyclic GMP phosphodiesterase

Question 24

Cell-surface receptor that binds a specific cytokine or hormone and acts through the JAK–STAT signaling pathway. (Figure 15–56)

Answer 24

cytokine receptor

Question 25

Enzyme activated by certain cell-surface receptors (tyrosine-kinase-associated receptors) that transmits the receptor signal onward by phosphorylating target cytoplasmic proteins on tyrosine side chains.

Answer 25

cytoplasmic tyrosine kinase

Question 26

Single-pass transmembrane signal protein displayed on the surface of cells that binds to the Notch receptor protein on a neighboring cell - activating a contact-dependent signaling mechanism.

Answer 26

Delta

Question 27

see adaptation

Answer 27

desensitization

Question 28

Lipid produced by the cleavage of inositol phospholipids in response to extracellular signals. Composed of two fatty acid chains linked to glycerol - it serves as a small signaling molecule to help activate protein kinase C (PKC). (Figure 15–28)

Answer 28

diacylglycerol (DAG)

Question 29

Scaffold protein recruited to the Frizzled family of cell-surface receptors upon their activation by Wnt binding that helps relay the signal to other signaling molecules.

Answer 29

Dishevelled

Question 30

Specialized animal cell that secretes a hormone into the blood. Usually part of a gland - such as the thyroid or pituitary gland.

Answer 30

endocrine cell

Question 31

A major type of cell-surface receptor that has a cytoplasmic domain that either has enzymatic activity or is associated with an intracellular enzyme. In either case - the enzymatic activity is stimulated by an extracellular ligand binding to the receptor. (Figure 15–6)

Answer 31

enzyme-coupled receptor

Question 32

One of a family of membrane-bound protein ligands for the Eph receptor tyrosine kinases (RTKs) that - among many other functions - stimulate repulsion or attraction responses that guide the migration of cells and nerve cell axons during animal development.

Answer 32

ephrin

Question 33

Small gas molecule that is a plant growth regulator influencing plant development in various way including promoting fruit ripening - leaf abscission - and plant senescence and functioning as a stress signal in response to wounding - infection - and flooding.

Answer 33

ethylene

Question 34

Any secreted or cell-surface chemical signal that binds to receptors and regulates the activity of the cell expressing the receptor.

Answer 34

extracellular signal molecule

Question 35

Cytoplasmic tyrosine kinase present at cell–matrix junctions (focal adhesions) in association with the cytoplasmic tails of integrins.

Answer 35

focal adhesion kinase (FAK)

Question 36

Family of cell-surface receptors that are seven-pass transmembrane proteins that resemble GPCRs in structure but do not generally work through the activation of G proteins. Activated by Wnt binding to recruit the scaffold protein Dishevelled - which helps relay the signal to other signaling molecules.

Answer 36

Frizzled

Question 37

A trimeric GTP-binding protein with intrinsic GTPase activity that couples GPCRs to enzymes or ion channels in the plasma membrane. (Table 15–3 - p. 846)

Answer 37

G protein (trimeric GTP-binding protein)

Question 38

A seven-pass cell-surface receptor that - when activated by its extracellular ligand - activates a G protein - which in turn activates either an enzyme or ion channel in the plasma membrane. (Figures 15–6 and 15–21)

Answer 38

G-protein-coupled receptor (GPCR)

Question 39

Member of a family of enzymes that phosphorylates multiple serines and threonines on a GPCR to produce receptor desensitization. (Figure 15–42)

Answer 39

GPCR kinase (GRK)

Question 40

Class of G protein that couples GPCRs to phospholipase C-β to activate the inositol phospholipid signaling pathway.

Answer 40

Gq

Question 41

Protein that binds to a GTPase and inhibits it by stimulating its GTPase activity - causing the enzyme to hydrolyze its bound GTP to GDP. (Figure 15–8)

Answer 41

GTPase-activating protein (GAP)

Question 42

Protein that binds to a GTPase and activates it by stimulating it to release its tightly bound GDP - thereby allowing it to bind GTP in its place. (Figure 15–8)

Answer 42

guanine nucleotide exchange factor (GEF)

Question 43

Secreted extracellular signal molecule that has many different roles controlling cell differentiation and gene expression in animal embryos and adult tissues. Excessive Hedgehog signaling can lead to cancer.

Answer 43

Hedgehog protein

Question 44

Signal molecule secreted by an endocrine cell into the bloodstream - which can then carry the signal to distant target cells.

Answer 44

hormone

Question 45

Inhibitory proteins that bind tightly to NFκB dimers and hold them in an inactive state within the cytoplasm of unstimulated cells.

Answer 45

IκB

Question 46

Protein with four or five immunoglobulin-like domains and two or three fibronectin-type-III-like domains; located on the cell surface and thought to serve as co-receptors for Hedgehog proteins.

Answer 46

iHog

Question 47

Trimeric G protein that can regulate ion channels and inhibit the enzyme adenylyl cyclase in the plasma membrane. (Table 15–3 - p. 846)

Answer 47

inhibitory G protein (Gi)

Question 48

Small intracellular signaling molecule produced during activation of the inositol phospholipid signaling pathway. Acts to release Ca2+ from the endoplasmic reticulum. (Figures 15–28 and 15–29)

Answer 48

inositol 1 -4 -5-trisphosphate (IP3)

Question 49

Intracellular signaling pathway that starts with the activation of phospholipase C and the generation of IP3 and diacylglycerol (DAG) from inositol phospholipids in the plasma membrane. The DAG helps to activate protein kinase C. (Figures 15–28 and 15–29)

Answer 49

inositol phospholipid signaling pathway

Question 50

Compact protein module - found in many intracellular signaling proteins - that binds to a particular structural motif (e.g. - a short peptide sequence - a covalent modification - or another protein domain) in another protein or lipid.

Answer 50

interaction domain

Question 51

Ion channel found at chemical synapses in the postsynaptic plasma membranes of nerve and muscle cells. Opens only in response to the binding of a specific extracellular neurotransmitter. The resulting inflow of ions leads to the generation of a local electrical signal in the postsynaptic cell. (Figures 15–6 and 11–35)

Answer 51

ion-channel-coupled receptor (transmitter-gated ion channel - ionotropic receptor)

Question 52

Gated Ca2+ channel in the ER membrane that opens on binding cytosolic IP3 - releasing stored Ca2+ into the cytosol. (Figure 15–29)

Answer 52

IP3-gated Ca2+-release channel (IP3 receptor)

Question 53

Signaling pathway activated by cytokines and some hormones - providing a rapid route from the plasma membrane to the nucleus to alter gene transcription. Involves cytoplasmic Janus kinases (JAKs) - and signal transducers and activators of transcription (STATs).

Answer 53

JAK–STAT signaling pathway

Question 54

Cytoplasmic tyrosine kinases associated with cytokine receptors - which phosphorylate and activate transcription regulators called STATs.

Answer 54

Janus kinases (JAKs)

Question 55

Intracellular signaling pathway in which one protein kinase - activated by phosphorylation - phosphorylates the next protein kinase in the sequence - and so on - relaying the signal onward.

Answer 55

kinase cascade

Question 56

Co-receptor bound by Wnt proteins in the regulation of β-catenin proteolysis.

Answer 56

LDL-receptor-related protein (LRP)

Question 57

Common type of receptor serine/threonine kinase in plants that contains a tandem array of leucine-rich repeat sequences in its extracellular portion.

Answer 57

leucine-rich repeat (LRR) receptor kinases

Question 58

Extracellular signal molecule that acts on neighboring cells.

Answer 58

local mediator

Question 59

An intracellular signaling module composed of three protein kinases - acting in sequence - with MAP kinase as the third. Typically activated by a Ras protein in response to extracellular signals. (Figure 15–49)

Answer 59

MAP kinase module (mitogen-activated protein kinase module)

Question 60

A single-subunit enzyme that converts GTP to GDP (also called small monomeric GTP-binding proteins). Cycles between an active GTP-bound form and an inactive GDP-bound form and frequently acts as a molecular switch in intracellular signaling pathways.

Answer 60

monomeric GTPase

Question 61

The TOR of mammalian cells - which exists in two functionally distinct multiprotein complexes.

Answer 61

mTOR

Question 62

Latent transcription regulator that is activated by various intracellular signaling pathways when cells are stimulated during immune - inflammatory - or stress responses. Also has important roles in animal development. (Figure 15–62)

Answer 62

NFκB protein

Question 63

Gaseous signal molecule that is widely used in cell–cell communication in both animals and plants. (Figure 15–40)

Answer 63

nitric oxide (NO)

Question 64

Enzyme that synthesizes nitric oxide (NO) by the deamination of arginine. (Figure 15–40B)

Answer 64

NO synthase (NOS)

Question 65

Transmembrane receptor protein (and latent transcription regulator) involved in many cell-fate choices in animal development - for example in the specification of nerve cells from ectodermal epithelium. Its ligands are cell-surface proteins such as Delta and Serrate. (Figure 15–59)

Answer 65

Notch

Question 66

Intracellular receptors for hydrophobic signal molecules such as steroid and thyroid hormones and retinoic acid. The receptor-ligand complex acts as a transcription factor in the nucleus. (Figure 15–65)

Answer 66

nuclear receptor superfamily

Question 67

G-protein-coupled receptors on the modified cilia of olfactory receptor neurons that recognize odors. The receptors activate adenylyl cyclase via an olfactory-specific G protein (Golf) and resultant increases in cAMP open cyclic-AMP-gated cation channels - allowing Na+ influx and depolarization and initiation of a nerve impulse.

Answer 67

olfactory receptors

Question 68

Short-range cell–cell communication via secreted signal molecules that act on neighboring cells. (Figure 15–2)

Answer 68

paracrine signaling

Question 69

Transmembrane protein predicted to cross the plasma membrane 12 times; much is in intracellular vesicles and some is on the cell surface where it binds the Hedgehog protein.

Answer 69

Patched

Question 70

Membrane inositol phospholipid (a phosphoinositide) that is cleaved by phospholipase C into IP3 and diacylglycerol at the beginning of the inositol phospholipid signaling pathway. It can also be phosphorylated by PI 3-kinase to produce PIP3 docking sites for signaling proteins in the PI-3-kinase–Akt signaling pathway. (Figures 15–28 and 15–53)

Answer 70

phosphatidylinositol 4 -5-bisphosphate [PI(4 -5)P2 - PIP2]

Question 71

A lipid containing a phosphorylated inositol derivative. Minor component of the plasma membrane - but important in demarking different membranes and for intracellular signal transduction in eukaryotic cells. (Figure 15–52)

Answer 71

phosphoinositide

Question 72

Membrane-bound enzyme that is a component of the PI-3-kinase–Akt intracellular signaling pathway. It phosphorylates phosphatidylinositol 4 -5-bisphosphate at the 3 position on the inositol ring to produce PIP3 docking sites in the membrane for other intracellular signaling proteins. (Figure 15–53)

Answer 72

phosphoinositide 3-kinase (PI 3-kinase)

Question 73

Membrane-bound enzyme that cleaves inositol phospholipids to produce IP3 and diacylglycerol in the inositol phospholipid signaling pathway. PLCβ is activated by GPCRs via specific G proteins - while PLCγ is activated by RTKs. (Figure 15–55)

Answer 73

phospholipase C (PLC)

Question 74

Reaction in which a phosphate group is covalently coupled to another molecule.

Answer 74

phosphorylation

Question 75

Photoprotein associated with the plant plasma membrane that senses blue light and is partly responsible for phototropism.

Answer 75

phototropin

Question 76

Plant photoprotein that senses light via a covalently attached light-absorbing chromophore - which changes its shape in response to light and then induces a change in the protein’s conformation. Plant phytochromes are dimeric - cytoplasmic serine/threonine kinases - which respond differentially and reversibly to red and far-red light to alter cell behavior.

Answer 76

phytochrome

Question 77

Intracellular signaling pathway that stimulates animal cells to survive and grow. (Figure 15–53)

Answer 77

PI-3-kinase–Akt pathway

Question 78

Signal molecule that helps coordinate growth and development. Examples are ethylene - auxins - gibberellins - cytokinins - abscisic acid - and the brassinosteroids.

Answer 78

plant growth regulator (plant hormone)

Question 79

Protein domain found in some intracellular signaling proteins. Some PH domains in intracellular signaling proteins bind to phosphatidylinositol 3 -4 -5-trisphosphate produced by PI 3-kinase - bringing the signaling protein to the plasma membrane when PI 3-kinase is activated.

Answer 79

pleckstrin homology domain (PH domain)

Question 80

Short - single - nonmotile cilium lacking dynein that arises from a centriole and projects from the surface of many animal cell types. Some signaling proteins are concentrated in the primary cilium. (Figure 15–38)

Answer 80

primary cilium

Question 81

Ca2+-dependent protein kinase that - when activated by diacylglycerol and an increase in the concentration of cytosolic Ca2+ - phosphorylates target proteins on specific serine and threonine residues. (Figure 15–29)

Answer 81

protein kinase C (PKC)

Question 82

Enzyme that catalyzes phosphate removal from amino acids of a target protein.

Answer 82

protein phosphatase

Question 83

Enzyme that removes phosphate groups from phosphorylated tyrosine residues on proteins.

Answer 83

protein tyrosine phosphatase

Question 84

Member of the Rho family of monomeric GTPases that regulate the actin and microtubule cytoskeletons - cell-cycle progression - gene transcription - and membrane transport.

Answer 84

Rac

Question 85

Monomeric GTPase of the Ras superfamily that helps to relay signals from cell-surface receptor tyrosine kinase receptors to the nucleus - frequently in response to signals that stimulate cell division. Named for the ras gene - first identified in viruses that cause rat sarcomas. (Figure 3–67)

Answer 85

Ras (Ras protein)

Question 86

Large superfamily of monomeric GTPases (also called small GTP-binding proteins) of which Ras is the prototypical member. (Table 15–5 - p. 854)

Answer 86

Ras superfamily

Question 87

Ras GTPase-activating proteins; increase the rate of hydrolysis of bound GTP by Ras - thereby inactivating Ras.

Answer 87

Ras-GAPs

Question 88

Ras guanine nucleotide exchange factors; stimulate the dissociation of GDP and the subsequent uptake of GTP from the cytosol - thereby activating Ras.

Answer 88

Ras-GEFs

Question 89

Intracellular signaling pathway that relays signals from activated receptor tyrosine kinases to effector proteins in the cell including transcription regulators in the nucleus.

Answer 89

Ras–MAP-kinase signaling pathway

Question 90

Any protein that binds a specific signal molecule (ligand) and initiates a response in the cell. Some are on the cell surface - while others are inside the cell. (Figure 15–3)

Answer 90

receptor

Question 91

Cell-surface receptor with an extracellular ligand-binding domain and an intracellular kinase domain that phosphorylates signaling proteins on serine or threonine residues in response to ligand binding. The TGFβ receptor is an example. (Figure 15–57)

Answer 91

receptor serine/threonine kinase

Question 92

Cell-surface receptor with an extracellular ligand-binding domain and an intracellular kinase domain that phosphorylates signaling proteins on tyrosine residues in response to ligand binding. (Figure 15–43 and Table 15–4 - p. 850)

Answer 92

receptor tyrosine kinase (RTK)

Question 93

A GAP protein that binds to a trimeric G protein and enhances its GTPase activity - thus helping to limit G-protein-mediated signaling. (Figure 15–8)

Answer 93

regulator of G protein signaling (RGS)

Question 94

A monomeric Ras-related GTPase that in its active form (Rheb-GTP) activates mTOR - which promotes cell growth.

Answer 94

Rheb

Question 95

Member of the Rho family of monomeric GTPases that regulate the actin and microtubule cytoskeletons - cell-cycle progression - gene transcription - and membrane transport.

Answer 95

Rho

Question 96

Family of monomeric GTPases within the Ras superfamily involved in signaling the rearrangement of the cytoskeleton. Includes Rho - Rac - and Cdc42. (Table 15–5 - p. 854)

Answer 96

Rho family

Question 97

Seven-span membrane protein of the GPCR family that acts as a light sensor in rod photoreceptor cells in the vertebrate retina. Contains the light-sensitive prosthetic group retinol. (Figure 15–39)

Answer 97

rhodopsin

Question 98

Photoreceptor cell in the vertebrate retina that is responsible for noncolor vision in dim light.

Answer 98

rod photoreceptor (rod)

Question 99

A regulated Ca2+ channel in the ER membrane that opens in response to rising Ca2+ levels and thus amplifies the Ca2+ signal.

Answer 99

ryanodine receptor

Question 100

Small intracellular signaling molecule that is formed or released for action in response to an extracellular signal and helps to relay the signal within the cell. Examples include cyclic AMP - cyclic GMP - IP3 - Ca2+ - and diacylglycerol.

Answer 100

second messenger (small intracellular mediator)

Question 101

Enzyme that phosphorylates specific proteins on serine or threonines.

Answer 101

serine/threonine kinase

Question 102

Src homology region 2 - a protein domain present in many signaling proteins. Binds a short amino acid sequence containing a phosphotyrosine. (Panel 3–2 - pp. 142–143)

Answer 102

SH2 domain

Question 103

Latent transcription regulators that are phosphorylated and activated by receptor serine/threonine kinases and carry the signal from the cell surface to the nucleus. (Figure 15–57)

Answer 103

Smad family

Question 104

Seven-pass transmembrane protein with a structure very similar to a GPCR but does not seem to act as a Hedgehog receptor or as an activator of G proteins; it is controlled by the Patched and iHog proteins.

Answer 104

Smoothened

Question 105

Family of cytoplasmic tyrosine kinases (pronounced “sark”) that associate with the cytoplasmic domains of some enzyme-linked cell-surface receptors (for example - the T cell antigen receptor) that lack intrinsic tyrosine kinase activity. They transmit a signal onward by phosphorylating the receptor itself and specific intracellular signaling proteins on tyrosines. (Figure 3–10)

Answer 105

Src (Src protein family)

Question 106

Latent transcription regulator that is activated by phosphorylation by Janus kinases (JAKs) and enters the nucleus in response to signaling from receptors of the cytokine receptor family. (Figure 15–56)

Answer 106

STAT (signal transducer and activator of transcription)

Question 107

Hormones - including cortisol - estrogen - and testosterone - that are hydrophobic lipid molecules derived from cholesterol that activate intracellular nuclear receptors.

Answer 107

steroid hormones

Question 108

G protein that - when activated - activates the enzyme adenylyl cyclase and thus stimulates the production of cyclic AMP. (Table 15–3 - p. 846)

Answer 108

stimulatory G protein (Gs)

Question 109

Intercellular signaling performed by neurons that transmit signals electrically along their axons and release neurotransmitters at synapses - which are often located far away from the neuronal cell body.

Answer 109

synaptic signaling

Question 110

Large - serine/threonine protein kinase that is activated by the PI-3-kinase–Akt signaling pathway and promotes cell growth.

Answer 110

TOR

Question 111

Large family of structurally related secreted proteins that act as hormones and local mediators to control a wide range of functions in animals - including during development. It includes the TGFβ/activin and bone morphogenetic protein (BMP) subfamilies. (Figure 15–57)

Answer 111

transforming growth factor-β superfamily (TGFβ superfamily)

Question 112

see G protein

Answer 112

trimeric GTP-binding protein

Question 113

Enzyme that phosphorylates specific proteins on tyrosines.

Answer 113

tyrosine kinase

Question 114

Cell-surface receptor that functions similarly to RTKs - except that the kinase domain is encoded by a separate gene and is noncovalently associated with the receptor polypeptide chain.

Answer 114

tyrosine-kinase-associated receptor

Question 115

Member of a family of secreted signal proteins that have many different roles in controlling cell differentiation - proliferation - and gene expression in animal embryos and adult tissues.

Answer 115

Wnt protein

Question 116

Signaling pathway activated by binding of a Wnt protein to its cell-surface receptors. The pathway has several branches. In the major (canonical) branch - activation causes increased amounts of β-catenin to enter the nucleus - where it regulates the transcription of genes controlling cell differentiation and proliferation. Overactivation of the Wnt/β-catenin pathway can lead to cancer. (Figure 15–60)

Answer 116

Wnt/β-catenin pathway