Bim plays an important role in the response to ABT-737. (A) Thymocytes and BM-derived B cells from wt, Bim^−/−, Noxa^−/−, Puma^−/−, Bmf^−/−, Bax^−/−, Bak^−/−, or Bax^−/−Bak^−/− mice were cultured in the absence or presence of increasing doses of ABT-737, and their viability determined after 24 hours. EC₅₀ values are represented as a heat map. Blue represents sensitivity, and red, resistance. (B) The hematopoietic system of lethally irradiated mice was reconstituted with WT, Bim^−/−, Noxa^−/−, Puma^−/−, or Bax^−/−Bak^−/− fetal liver cells retrovirally transduced with an empty vector or a vector encoding Bcl-2. Eight weeks after reconstitution, the viability of the resulting cells in response to treatment with several doses of ABT-737 was analyzed in culture as described in Figure 2; n = 3 mice per group, 3 independent experiments (except for Bax^−/−Bak^−/− n = 1 because of the difficulty to obtain viable animals). Values represent the mean of EC₅₀ ± SEM, detailed in supplemental Table 2.