Axl blockade chemosensitizes AML cells in vivo. (A) Morphometric analysis of phospho-Histone H3⁺ cells indicated inhibition of proliferation of MV4-11 AML cells in vivo by BGB324 (25 mg/kg) (n = 4/5; *P < .05). (B-C) Representative immunohistochemistry pictures of phospho-Histone H3 stainings on sections from MV4-11 control- and BGB324-treated tumors (bar represents 50 µm). (D) BGB324 (12.5 mg/kg) exerted a chemosensitizing effect on efficacy of Doxo (3 mg/kg) in MV4-11 xenografts in vivo (n = 4/4/3/6; *P < .05). (E) Analysis of immunohistochemistry for phospho-Histone H3 confirmed an additive effect of Doxo and BGB324 on proliferation of MV4-11 cells in vivo (n = 4/4/3/4; *P < .05; #P < .05).