Deck 6: Cytoplasmic Signaling Circuitry Programs Many of the Traits of Cancer

Question 1

Which of the following signaling pathways is in the correct order?

A)Receptor → Sos → Grb2 → Ras
B)Receptor → Ras → Sos → Grb2
C)Receptor → Sos → Ras → Grb2
D)Receptor → Grb2 → Ras → Sos
E)Receptor → Grb2 → Sos → Ras

Answer 1

Receptor → Grb2 → Sos → Ras

Question 2

Which of the following statements about AKT is FALSE?

A)AKT is activated downstream of PI3K.
B)AKT activation may inhibit apoptosis through downstream inactivation of Bad.
C)AKT activation may result in activation of mTOR.
D)AKT is tethered to the plasma membrane by PIP3.
E)None of the above.

Answer 2

None of the above.

Question 3

Which of the following molecules is NOT a downstream effector of Ras?

A)Ral-GEFs
B)PI3K
C)Grb2
D)Raf
E)None of the above

Answer 3

Grb2

Question 4

Following serum starvation,if normal fibroblasts were treated with cycloheximide to shut down cellular protein synthesis,then,when exposed to fresh serum,the cells would

A)Continue to remain viable in a quiescent state.
B)Express immediate early genes.
C)Enter a state of senescence.
D)Die.
E)None of the above.

Question 5

Which of the following does NOT occur downstream of epidermal growth factor binding to its receptor?

A)NF1 is phosphorylated.
B)NF1 levels are increased.
C)Ras is GTP-loaded.
D)The MAPK pathway is activated.
E)None of the above.

Question 6

What happens in cells following stimulation with growth factors?

A)The transcription of all genes required for growth and replication occurs immediately.
B)There is a delay of several hours before transcription of genes needed for growth occurs.
C)Some genes required for growth are transcribed immediately,while others are transcribed later,after new transcription factors have been synthesized.
D)Cell death occurs.
E)None of the above.

Question 7

In normal cells,Ras-GAPs trigger GTPase activity in order to

A)Maintain Ras in its active state.
B)Enhance downstream signaling by Ras effectors.
C)Promote cellular proliferation.
D)Inactivate Ras signaling.
E)A and B.

Question 8

Which of the following pathways activated downstream of Ras can result in reorganization of the cytoskeleton,playing a role in cell motility?

A)MEK
B)PI3K
C)Ral BP1
D)Erk1
E)None of the above

Question 9

Which of the following domains of Src is its catalytic domain?

A)SH1
B)SH2
C)SH3
D)C-terminus
E)N- terminus

Question 10

SH2 domains of tyrosine kinases function to

A)Catalyze activation of downstream pathways.
B)Act as receptors for phosphotyrosine-containing oligopeptide ligands.
C)Localize the protein to specific sites in the cell.
D)B and C.
E)None of the above.

Question 11

Which of the following is NOT true of the son of sevenless Sos)protein?

A)It is a guanine nucleotide exchange factor GEF).
B)It is a GTPase-activating protein GAP).
C)It is able to activate Ras.
D)It was initially identified in Drosophila melanogaster.
E)None of the above.

Question 12

Which of the following is NOT true of β-catenin?

A)It binds directly to the Wnt protein.
B)It associates with Tcf/Lef transcription factors in the nucleus,driving cell proliferation.
C)It can be degraded when bound to active GSK-3β.
D)It exists in a soluble pool in the cytosol.
E)None of the above.