sb743921 is an inhibitor of kinesin spindle protein (ksp) with ki value of 0.1nm .as an inhibitor of mitotic kinesin ksp, sb743921 causes cell cycle arrest in mitosis, results in cell death. sb743921 is developed to treat for cancers. sb743921 is a potent and selective inhibitor. in the affinity assays, sb743921 shows ki values of 0.1nm and 0.12nm for human ksp and mouse ksp, respectively. it has no affinity with other kinesins. in the cellular assay, sb743921 exerts anti-proliferation efficacy in skov3, colo205, mv522 and mx1 with ic50 values of 0.02nm, 0.07nm, 1.7nm and 0.06nm. moreover, sb743921 is shown to have activity against human tumor xenografts colo205, mcf-7, sk-mes, h69, ovcar-3, ht-29, mda-mb-231 and a2780. sb743921 is also effective against p388 lymphocytic leukemia xenografts in mice .
 jackson j r, gilmartin a, dhanak d, et al. a second generation ksp inhibitor, sb-743921, is a highly potent and active therapeutic in preclinical models of cancer. proceedings of the american association for cancer research, 2006, 2006(2): b11.