Question

1. Which of the following is NOT an example of a proto-oncogene that could mutate to become an oncogene?

   	a.	p53
   	b.	erbB
   	c.	ras
   	d.	raf

Answer 1

protooncogenes are normally present in the cell, these genes promote cell cycle progression,erbB encodes a growth factor receptor, ras and raf encodes G proteins involved in the growth factor signaling pathway, so functional products encoded by these three genes promote cell cycle progression if a mutation occurs such that these genes get gain of function mutation or become constitutively active, the cell divides even without the presence of a signal. so these three are protooncogenes.

p53 is a tumor supressor gene, which regulate the cell cycle progression so the answer is a) p53.