Vincristine is a plant alkaloid isolated from Vinca Rosea that irreversibly blocks mitosis by binding to tubulin (Ki = 85 nM) and inhibiting tubulin polymerization. It arrests cell cycle in G2/M-phase by blocking mitotic spindle formation. Vincristine is exported from cells via the ATP-binding cassette transporter P-glycoprotein, but not by multidrug resistance-associated protein. MW: 923.04. Purity ≥95%