Radioprotective effect of the H2K-BCL-2 transgene. (A) Survival of H2K-BCL-2 transgenic and wild-type mice after single dose irradiation at the doses indicated. Graph is based on survival data from 84 wild-type and 51 transgenic mice, 2 (extreme values) to 17 (mid-range) mice were assayed per irradiation dose. The 30-day survival of wild-type mice differs significantly from transgenic mice at 6.5, 7, and 8 Gy (P values [Fisher's exact test] are .0359, .0002, and .0310, respectively). (B) Long-term survival of H2K-BCL-2 transgenic mice after lethal total body irradiation, 9.5 Gy, split dose. The difference in 90-day survival is highly significant, P < .0001 (Fisher's exact test). (C) Survival of reconstituted Balb/c mice after split dose 9.5-Gy irradiation. These mice were reconstituted with bone marrow from H2K-BCL-2 transgenic mice and wild-type littermates at 3 to 4 months before irradiation.