MEK inhibition increases Bcl-2 dependence. (A) KMS18, (B) MM.1s, (C) KMS12BM, and (D) OCI-My5 were treated with 1 ng/ml IL-6 and/or 10 μM U0126 for 24 hours, and protein lysates were prepared and then subjected to coimmunoprecipitation with anti-Bim antibodies. The resulting protein complexes and protein input (WCL) were examined by western blot analysis using anti-Bim, anti-Mcl-1, anti-Bcl-xL, anti-Bcl-2, and anti-actin. The amount of coprecipitated protein was quantitated by densitometry and normalized to control. Figures are representative of 2 to 3 independent experiments.