Estramustine phosphate but not estramustine inhibits the interaction of microtubule associated protein 2 (MAP2) with actin filaments.

The effect of estramustine and estramustine phosphate (EP) on the interaction of microtubule associated protein 2 (MAP2) with actin has been examined. We show that (a) neither estramustine nor EP influences actin polymerisation (b) EP, but not estramustine, reduces the amount of MAP2 which co-sediments with F-actin in a dose-dependent manner and (c) EP decreases the MAP2-induced crosslinking of F-actin into gelled networks. The data suggest, that unlike estramustine, EP interacts with MAP2 and modifies its interaction not only with microtubules but also with actin filaments.