Dasatinib blocks the spontaneous proliferation of MM patient ECs (MMECs) by preventing constitutive VEGF/VEGFR2 loop. (A) Proliferation of MMECs cultured in serum-free medium (SFM) in the absence or in the presence of dasatinib 50 nM for 2, 4, and 8 days (10⁴ cells/well). Data were expressed as percentage of growth inhibition. Error bars represent SD of triplicate experiments. (B) Whole lysates prepared from cells treated as described were examined by SDS-PAGE analysis, as indicated. (C) VEGF concentrations were measured in triplicate by ELISA in conditioned media (CM) of MMECs cultured with dasatinib (10-25 nM) for 48 hours. Protein levels of secreted VEGF in the CM were also assessed by Western blotting analysis, as indicated.