Protein analysis of primary ALL cells is consistent with whole-cell ABT-737 response and BH3 profiles. (A) Western blot analysis of CHAPS lysates (20 μg) shows detectable expression of BCL-2, MCL-1, BIM, and BID among primary ALL cells. (B) Purified GST-BCL-XL and GST-BCL-2 (1 and 3 ng) were run next to 5 independent ALL lysates (10 μg) to quantitate BCL-XL (top panel) and BCL-2 (middle panel). Primary ALL lysates with better equal loading reveal clearer BIM levels among samples (bottom panel). (C) BCL-2, BIM, and BID are also complexed in primary ALL cells. Anti–BCL-2 immunoprecipitation of ALL primary cells (50 μg). Immunoprecipitation pellet (i.p.) and 10% of total lysate used for immunoprecipitation (input) were loaded. BIM and BID are complexed to BCL-2 in amounts proportional to whole-cell amounts.