Tubulysin A is a myxobacterial product that can function as an antiangiogenic agent in many in vitro assays. Tubulysin A is a novel antibiotic, which is anti-microtubule, anti-mitotic, apoptosis inducer, anticancer, anti-angiogenic, and antiproliferative. Tubulysins are cytotoxic peptides, which include 9 members (A-I). 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.