Depletion of endogenous c-Kit inhibits EPC adhesion. (A) EPCs were transfected with c-Kit siRNA (K1) or with the scrambled sequence (scramble) and lysed. The filter was IB with an anti–c-Kit and an anti–β-actin antibody. (B) Adhesion was performed with EPCs transfected with the scramble or the K1 siRNA (48h). (C) EPCs pretreated with 5 or 10 μM imatinib mesylate were untreated or treated with the soluble KitL (10 ng/mL). The filter was IB with an anti–p–c-Kit and an anti–c-Kit antibody. M07e cells were used as positive control (+). (D) Adhesion was performed with EPCs untreated or treated with 5 or 10 μM imatinib mesylate or with a neutralizing anti-PDGFRβ antibody (30 μg/mL).²³  Adherent cells were counted for statistical analysis (data in B and D are the mean ± SD; *P < .05 control vs experimental groups). (E) Fibroblasts were analyzed for c-Kit and mbKitL expression by FACS analysis. Light lines indicate preimmune mouse IgG used as a negative control; dark lines, c-Kit or mbKitL expression. (F) Adhesion was performed on fibroblasts with EPCs pretreated with 5 or 10 μM imatinib mesylate or K44. Adherent cells were counted for statistical analysis (data are the mean ± SD; *P < .05 control vs experimental groups). Four different experiments were performed with similar results.