A macrolide anticancer agent. Similar to paclitaxel (Cat. No. 1567-25), epothilone B induces microtubule polymerization and stabilizes microtubules against depolymerization conditions. In addition to promoting tubulin polymerization and stabilization of microtubules, this agent is cytotoxic for cells overexpressing P-glycoprotein, a characteristic that distinguishes it from the taxanes. Also induces G2-M cell cycle arrest (EC50= 3 - 92 nM). MW: 507.68. Purity ≥98% by HPLC