Tubulysin M is a novel, highly cytotoxic and naturally occuring peptide with anti-microtubule, anti-mitotic, apoptosis inducer, anticancer, anti-angiogenic, and antiproliferative activities. It is extracted from the myxobacterial species Archangium geophyra and Angiococcus disciformis. Tubulysin A has potential application as an anticancer agent. It arrests
cells in the G2/M phase. Tubulysin A inhibits polymerization more
efficiently than vinblastine and induces depolymerization of isolated
microtubules. Tubulysin A has potent cytostatic effects on various tumor
cell lines with IC₅₀ in the picomolar range.