VEGF up-regulates Mcl-1 and protects patient MM cells from FBS starvation-induced apoptosis. (A) VEGF up-regulates Mcl-1 expression in patient MM cells. Patient MM cells were starved overnight in RPMI 1640 with 0.5% FBS, followed by culture for 6 hours in the absence or presence of either IL-6 (50 ng/mL) or VEGF (50 ng/mL). Cells lysates (30 μg per lane) were analyzed by Western blot analysis using indicated antisera. Actin was used as a loading control. (B) FBS starvation-induced apoptosis is inhibited by VEGF. Patient BM mononuclear cells were cultured for 48 hours in RPMI 1640 with 10% or 2% FBS, in the presence or absence of VEGF (25 ng/mL). The subset of MM cells (CD38⁺⁺ cells; left panel) and non-MM cells (CD38^+/- cells; right panel) was evaluated for apoptosis using Apo 2.7 staining. The percentage of apoptotic MM cells or non-MM cells cultured in control FBS 10% (upper lane), in FBS 2% (middle lane), and in FBS 2% supplemented with VEGF 25 ng/mL (bottom lane) is indicated.