BIM phosphorylation in CLL cells after coculture with HK cells. (A) CLL samples (n = 8) were cultured in the presence or absence of HK cells for 72 hours. Cell death was analyzed by PI staining in permeabilized cells. (B) CLL samples were cultured in the presence or absence of HK cells for 6 hours, and expression of BIM and β-actin was analyzed by immunoblotting. Data are representative of the responding cases. (C) CLL samples were cultured in the presence or absence of HK cells ± U0126 (10μM) for 6 hours, and expression of BIM, phospho-ERK1/2, and β-actin was analyzed by immunoblotting. (D) CLL samples were pretreated with U0126 (U0; 10μM) or left untreated as a control, before coculture with HK cells. After 48 hours, cell death was determined by annexin V/PI staining. Data are means of triplicate repeats (± SD).