This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Gene which inhibits cell cycle is - 
Select and explain. 
A. p53, B. RB, C. p16, D. Notch receptor
A: p53
Answer: A: p53 
Explanation: Answer-A. p53Cell cycle inhibitorsCIP/KIP family - p21, p27, p57INK4a/ARF family - p161 NK4a, pl4ARFA G1 arrest can result simply by the p53 induced expression of p21 WAF1/CIP1/Sdi1 P53 also down regulates the expression of cyclin A, providing a secondary break on cell cycle progression into the through the S phase.