The tumor suppressor gene p53 induces cell cycle arrest at:: (A) G2-M phase, (B) S-G2 phase, (C) G1-S phase, (D) G0 phase
Answer is C. G1/S check-point is controlled by p53 whereas G2/M check-point has both p53 dependent as well as independent mechanisms. p53 induces the synthesis of p21 which inhibits cyclin D/Cdk4. This results in stoppage of activation of Rb and cell cycle is arrested in G1/S phase. Fig:- Role of P53 in maintaining the integrity of the genome