An inhibitor of microtubule assembly cytotoxic to a variety of cancer cells including SKOV3 ovarian U87 glioblastoma and AsPC-1 pancreatic cancer cells (IC50s 36 77 and 285 nM respectively) induces complete tumor regression in a rat Yoshida AH13 sarcoma model at 10 mg/kg without inducing systemic or neurotoxicity