Question

1) Which ONE of the following is NOT TRUE about p16:

a)it is an oncogene
b)it is on the same pathway and hence seldom mutated in tumors when RB is

c)it is often mutated in cancers such as familial melanoma

d)it is encoded in the same gene locus as p19-ARF

e)It is a cyclin dependent kinase inhibitor (CKI)

2)Which ONE of the following is NOT a property of the transformed phenotype:

a)Induced by over expression of tumor suppressor genes

b)Anchorage independence

c)Infinite proliferative life span

d)Lower requirement for growth factors

e)Does not exhibit density-dependent inhibition of cell growth

3)Which ONE of the following is NOT true about DNA viruses and cancer:

a)HPV E6, HPV E7 and SV40 large T antigen are all viral oncoproteins encoded by DNA viruses

b)they encode viral oncoproteins that bind RB

c)viral oncoproteins do not originate from host genes

d)they encode viral oncoproteins that bind MDM2

4) Which ONE of the following is NOT TRUE about the JNK pathway:

a)Another name for the pathway is the stress activated pathway (SAPK)

b)JNK stands for Jun N-terminal kinase

c)It is activated by UV and osmolarity changes

d)it does not require scaffolding proteins for proper signaling

e)it is affected by phytochemicals such as resveratrol

5)Which ONE of the following is NOT TRUE about the online resources The Cancer Genome Atlas (TCGA) and cBioPortal:

a)they can help researchers understand the molecular basis of cancer

b)they can help distinguish tumor subtypes for better diagnosis

c) they allow many scientists around the world to access the data and further cancer research

d) they can help the average person diagnose themselves in the comfort of their own home

e) they can help identify genomic characteristics of tumors to improve treatment

6) Which ONE of the following statements is NOT TRUE about Ras signaling:

a)GEFs (guanine nucleotide exchange factors) convert inactive Ras to active Ras

b)Ras was identified in both the NIH 3T3 foci assay and as a viral oncogene

c)active Ras recruits Raf to the inner plasma membrane

d)~50% of Ras is bound to GTP in the active state in a normal cell

e)prenylation of its C-terminal tail is required for both wt and mutant Ras to be functional

Answer 1

1. Answer: Correct options is option (a).

a) Oncogene is responsible for cancer development but p16 is protein popularly known as tumor suppressor. It slows the division of cells by delaying the progression of the cell cycle from G1 to S phase and thus act as a tumor suppressor.

b) Normally, in RB (Retinoblastoma), active CDK (cyclin dependent kinase) signaling causes hyperphosphorylation of RB gene and eventually develop retinoblastoma. p16 inhibit the CDK and therefore preventing the retinoblastoma tumor (eye tumor).

c) p16 germline mutations have been reported during familial melanoma.

d) Tumor suppressors such as p16-INK4a and p19-ARF ( both are independent but overlaping genes) both encoded in the same locus known as CDKN2A and play important role in the induction and maintainance of permanent cell cycle arrest during cell senescence.

e) p16 is a cyclin dependent kinase inhibitor that inhibit cyclin dependent kinases and therefore called tumor suppressor protein.