Nilotinib increases melphalan sensitivity in MM cells in vivo. (A) MM.1S cells were injected subcutaneously into SCID mice (5 mice per group), and after the appearance of tumors, mice were treated with either DMSO, nilotinib (50 mg/kg, 5 days per week), melphalan (2 mg/kg, twice per week), or in combination. Line plots showing tumor volumes (with error bars indicating SDs) and representative images of tumors in different treatments are shown. (B) Tumors were lysed and evaluated for HR activity by in vitro strand exchange assay; error bars indicate SDs of experiments conducted in triplicate, and 2-tailed P values are derived by t test (∗P < .05-.001). DMSO, dimethyl sulfoxide; SD, standard deviation.