Antiapoptotic changes in CLL cells upon CD40 stimulation include ERK-mediated decrease in Bim levels. (A) Changes in expression of apoptosis regulators upon 48 hours of CD40 triggering were monitored by Western blot for the indicated proteins. Results are from a representative CLL sample from more than 10 patients studied. Equal protein loading was confirmed by staining for actin as loading control. (B) Time course of Bim-EL decrease monitored in 2 CLL samples. Shown are samples taken on consecutive days of coculture in absence or presence of CD40 stimulation. In sample 11 a decrease in Bim-EL can be observed on day 2, and in sample 12 on day 1. Position of Bim-EL is indicated by a triangle, the faster migrating species is probably the BimĪ±1 splice variant. (C) Effects of ERK inhibition on Bim levels and phosphorylated ERK. CLL cells were stimulated with CD40 in the presence of ERK inhibitor as indicated, and lysates were probed for Bim protein, phosphorylated and total ERK levels.
