MVs activate RTKs in BMSCs. (A) Activation of RTKs in BMSCs stimulated with MVs obtained from CLL patients at Rai stages 0 (MV1), I (MV2), or II (MV3) was analyzed on human phospho-RTK antibody array blots and the level of activation compared with the unstimulated control BMSCs. Activation of various RTKs was analyzed and presented as fold-activation by bar diagrams. (B) Lysates from BMSCs stimulated with MVs after treatment with the Axl-inhibitor, SKI-606 (SKI) or anti-VEGF neutralizing antibody (NAB) or left unstimulated or untreated were examined for the phosphorylation of AKT by Western blot. Treatment with SKI-606 showed substantial inhibition of MV-mediated activation of AKT; however, anti-VEGF antibody did not show any effect. Phosphorylation of Axl is also shown for comparison. Actin was used as loading control. (C) MVs obtained from CLL patients at various Rai stages (0, I, II) were analyzed for the presence of constitutively active Axl by Western blot with the use of a phospho-specific antibody to Axl. Actin was used as loading control.