K858 (72926-24-0) is a selective mitotic kinesin Eg5 inhibitor (IC50 = 1.3 μM) which acts in an ATP-noncompetitive manner1,2. It is at least 150-fold more selective for Eg5 than other members of the kinesin superfamily. K-858 blocks centrosome separation, activates the spindle checkpoint and induces mitotic arrest accompanied by the formation of monopolar spindles. Displays no effect on microtubule polymerization. Selectively displays antiproliferative effects via induction of mitotic cell death in cancer cells over nontransformed cells1.
1) Nakai et al. (2009), K858, a novel inhibitor of mitotic kinesin Eg5 and antitumor agent, induces cell death in cancer cells; Cancer Res., 69 3901
2) Indorato et al. (2013), STLC-resistant cell lines as tools to classify chemically divergent Eg5 targeting agents according to their mode of action and target specificity; Biochem. Pharmacol., Epub ahead of print Sept. 13