Figure 4.

Ectopic expression of Bax, Bcl-2, and E1B 19K. (A) Primary cell populations expressing E1A and/or Bax were generated by sequential infection with recombinant retroviral vectors expressing E1A (WZL-12S) then either bax (LPC-HAbax; gray bars) or a empty vector (LPC; black bars). Infected populations were plated in multiwell plates and analyzed for viability 24 h later without drug treatment. The MEF genotypes and E1A status are indicated below the graph. Shown is a representative graph of three separate experiments that all produced the same results. (B) Wild-type (circles), bax^−/− (triangles), or p53^−/− (squares) MEFs were first infected with retroviruses expressing E1A (WZL-12S) and then either Bcl-2 (LPC-bcl2; open symbols) or a control vector (LPC; closed symbols). After selection, cells were treated with adriamycin, and viability was determined after 24 h. (C) E1A-expressing populations were superinfected with a retrovirus expressing E1B 19K (LPC-19K) and analyzed as in B. The symbols are as described in B, except that open symbols represent cells coexpressing E1B 19K with E1A. Each point in B and C represents the average ± SD of data obtained from at least three separate experiments.