Question

Which of the following true about Rb in the cell cycle?

(a) Phosphorylation of Rb will lead to its inactivation

(b) Phosphorylation of Rb will also lead to inactivation of E2F

(c) Phosphorylation of E2F will promote cell cycle progression

(d) E2F is directly affected by Rb

The question was posed to me by my school principal while I was bunking the class.

This is a very interesting question from Overview of Cell Reproduction topic in chapter Chromosomal Changes During Meiosis of Cytogenetics

Answer 1

Right choice is (b) Phosphorylation of Rb will also lead to inactivation of E2F

The explanation is: Rb binds E2F and prevents cell cycle progression. If Rb is phosphorylated it will lead to release of E2F leading to continuation of the cell cycle.