A Cell Is Unable to Progress into the S Phase

Multiple Choice

A cell is unable to progress into the S phase of the cell cycle. Further studies indicate that the RB-E2F complex is unable to dissociate in this cell and thus remains together. Which of the following genes is MOST likely mutated?

A) a gene that encodes a cyclin-dependent kinase
B) a gene that encodes an acetylase
C) a gene that encodes an enzyme that removes phosphate groups from RB
D) a gene that encodes an enzyme that phosphorylates E2F
E) a gene that encodes the Ras protein