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
[{'content': 'Retinoblastoma gene regulates? \nSelect and explain. \nA. G1-s phase, B. G2 to M phase, C. G0 to G 1 Phase, D. S-G2 Phase', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 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.', 'role': 'assistant'}]