This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
Retinoblastoma gene regulates? 
Select and explain. 
A. G1-s phase, B. G2 to M phase, C. G0 to G 1 Phase, D. S-G2 Phase
A: G1-s phase
Answer: A: G1-s phase 
Explanation: harshmohan textbook of pathology 7th edition. *active form of RB gene :it blocks cell division by binding to the transcription factor E2F and this inhibits the cell from transcription of cell cycle related gene there by inhibiting the cell cycle at G1.