Chapter 5 Self-check questions

. The cyclin D-cdk4 complex phosphorylates C-terminal residues of pRB upon growth factor stimulation. Which one of the following events does this lead to?

The cyclin A gene is expressed upon release of HATs from pRB.

The cyclin E gene is expressed upon release of HDAC from pRB.

The cyclin E gene is down regulated upon release of HDAC from pRB.

The cyclin D gene is expressed upon release of HDAC from pRB.

. The G1 checkpoint (also known as the G1 restriction point) leads to which one of the following?

The arrest of the cell cycle in response to DNA damage to prevent its replication.

The arrest of the cell cycle in response to damaged and unreplicated DNA to ensure proper completion of S phase.

The arrest of chromosomal segregation in response to misalignment of the mitotic spindle.

The regulation of epigenetic modifications.

. Which one of the following statements concerning the retinoblastoma protein (pRB) is false?

pRB phosphorylation is carried out in a single step reaction.

pRB regulates the cell cycle by inhibiting the transition from G1 to S phase.

pRB can be bound to HDAC and E2F transcription factors at the same time.

Conformational changes in pRB result after phosphorylation and cause the release of HDAC and E2F.

. Which one of the following statements is false?

Cyclins and their associated cdks coordinate and regulate the passage of cells through the cell cycle.

The pairing of cyclins to cdks is non-specific.

Cyclin D is the first cyclin to be synthesized.

Cyclin D plays a role in the regulation and expression of the cyclin E gene.

. Which statement about the mechanisms of pRB action is true?

E2F release from pRB causes transcription of cyclin E target genes.

HDAC binds to the B-chain of pRB by an LXCXE motif and inhibits E2F target genes.

Phosphorylation of Ser567 by cyclin D-cdk4 causes E2F release.

pRB acts as a transcription factor to promote S phase progression.

. What was the first cdk inhibitor to be tested in clinical trials?

Gleevec.

Taxol.

Flavopiridol.

Vincristine.

. Which one of the following statements is false?

Over-expression of cyclin D by gene amplification is observed in about 15% of breast cancers.

Cyclin D enhances estrogen receptor- mediated transcription by binding to the hormone-binding domain.

EGFR exerts its mitogenic effect by the induction of cyclin D expression.

Experimental evidence suggests Cyclin D is a tumor suppressor gene.

. Which one of the following statements about aneuploidy is false?

It is the condition of having an abnormal chromosome number and content.

It may be caused by defects in centrosomes.

It is a common characteristic of human solid tumors.

It may be caused by an increased quantity of mitotic checkpoint proteins.

. All of the following drugs interfere with microtubule and spindle formation except:

Tamoxifen.

Vincristine.

Vinblastine.

Paclitaxel/taxol.

. Which technique can be used to directly visualize gene amplification of the cyclin D gene in the cell?

Polymerase chain reaction

Fluorescent in situ hybridization.

Immunopurification

DNase footprinting

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