ADCs Toxins, DM4 belongs to Maytansinoids which are a group of cytotoxins structurally similar to rifamycin, geldanamycin, and ansatrienin. Maytansinoids can bind to tubulin at or near the vinblastine-binding site, which interfere the formation of microtubules and depolymerize already formed microtubules, inducing mitotic arrest in the intoxicated cells.