Figure 8.

A role for E2F1 in DNA damage-induced thymocyte death. (A) Western blot analysis of E2F1 protein induction in thymocytes analyzed 22 h following treatment with etoposide (2 μM). (B) Viability assays. Thymocytes were prepared from 4–8-week-old mice and cell viability was analyzed 20 h following treatment with etoposide at concentrations ranging from 2 to 500 μM. (C) Viability assays. Thymocytes were prepared from six month-old mice and cell viability was analyzed 20 h following treatment with etoposide at concentrations ranging from 2 to 200 μM. (D) Flow cytometry profiles following CD4 and CD8 immunostaining of thymocytes from E2F1^+/+ or E2F1^−/− mice at either eight wk of age or six mo of age.