This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Concepts, Subject name: Pathology
[{'content': 'The tumor suppressor gene p53 induces cell cycle arrest at: \nSelect and explain. \nA. G2-M phase, B. S-G2 phase, C. G1-S phase, D. G0 phase', 'role': 'user'}, {'content': 'Answer: C \nExplanation: 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', 'role': 'assistant'}]