Cycle delay in irradiated cytochalasin‐induced polykaryons. Does cytoskeleton status affect cell cycle checkpoints?

Following exposure of CHO‐K1 cells to 137 Cs irradiation at doses up to 20Gy, a delay in G 2 was observed to occur in cells permitted to divide normally, while cells induced to become giants by means of cytochalasin B demonstrated a minimal delay in the transition 2C–8C suggesting that the inhibition of cytokinesis results in modification of one or more cell cycle checkpoints. We postulate that this may occur as a consequence of damage tolerance, or by a feedback loop resulting from the reorganisation of the cytoskeleton that precludes cytokinesis.