Coimmunoprecipitation of proapoptotic proteins with Mcl-1, Bcl-XL, and Bcl-2. MM.1s and KMS11 cell lines were treated with 2 μM ATO for 0, 6, and 24 hours. Protein lysates were prepared using 2% CHAPS buffer. (A) Mcl-1, (B) Bcl-XL, and (C) Bcl-2 proteins were immunoprecipitated with mAbs. Coimmunoprecipitated proteins were detected by Western blot using specific antibodies for Bak, Bax, Noxa, Bim, Puma, Mcl-1, Bcl-XL, and Bcl-2. The separated bands on each end of the panels represent the input for the IP. This lane contains 10% of the input, however only 60% of the immunoprecipitated protein was loaded in the gel. All bands represented are from the same experiment and same exposure of film.