Labelled Apatinib (A726150). Apatinib is an orally available, small molecule multitargeted tyrosine kinase inhibitor. Apatinib selectively inhibits the vascular endothelial growth factor receptor-2 (VEGFR2). Apatinib functions by inhibiting VEGF-mediated endothelial cell migration and proliferation thus blocking new blood vessel formation in tumor tissue. Recent studies have shown that Apatinib enhances the efficacy of conventional chemotherapeutical drugs in side population (SP) cells and ABCB1-overexpressing leukemia cells.