P53 IS NOT REQUIRED FOR REGULATION OF APOPTOSIS OR RADIOPROTECTION BYINTERLEUKIN-3

Primary interleukin-3 (IL-3)-dependent mast cell cultures from bone ma rrow of p53-null mice and littermate controls were established. Both p 53-null and wild-type cells entered apoptosis on IL-3 removal, showing that p53 is not required for entry into apoptosis after factor depriv ation. After X-irradiation, a lower proportion of the p53-null than wi ld-type cells underwent G2 arrest, but their radiosensitivity was simi lar, An IL-3-dependent cell line expressing wild-type p53 was used to show that cells die at a fixed time after X-irradiation rather than fr om a specific cell cycle point. (C) 1997 by The American Society of He matology.