Figure 5. Apoptosis in Sei1-null cells.

(A and B) Three independent preparations of primary MEFs per genotype were either irradiated with the indicated doses of UVC (A), or transduced with E1A and treated with low serum conditions or with adriamycin, as indicated (B). Apoptosis was measured by quantifying subG0 DNA content by FACS. (C) Thymocytes from three mice per genotype treated with 10 Gy of γ-radiation were isolated and apoptosis was measured 3 h post-radiation, as in (A) and (B). (D) Protein extracts of lung and spleen from the same irradiated mice as in (C) were immunoblotted against p53 or its target p21^Cip1. Actin was used as a loading control.