In the Absence of Growth Factors,the Retinoblastoma (RB)protein Binds a Transcription

Multiple Choice

In the absence of growth factors,the retinoblastoma (RB) protein binds a transcription activator called E2F,preventing the cell from entering S stage.A mutation in E2F occurs that causes RB to no longer bind it.This mutant E2F would be considered a(n)

A) oncogene.
B) proto-oncogene.
C) tumor supressor.
D) gain-of-function mutant.
E) growth factor.