<prompt> The tumor suppressor gene p 53 induces cell cycle arrest atG2_M phaseS_G2 phaseG2_SphaseG0phase  <response>: Ref Robbins 8e p290-291 ,9e p294 The cell cycle has its own internal controls called checkpoint, there are two main checkpoints ,one at the G2S transition and another at G2M In the G1S checkpoint ,cell cycle arrest is mostly mediated through p53, which induces the cell cycle inhibitor p21 Arrest of the cell cycle by the G2M checkpoint involves both p53 dependant mechanism As can be deduced from above mentioned information that the p53 is associated with both the types of checkpoint , however G2 M checkpoint can take place even without p53.hence option C is the preferred anwers 