For example, ring A is not essential to antimitotic activity. In vitro screening has identified fisetin as an antimitotic compound. Because of these interactions it is considered an antimitotic drug. Additionally, antimitotic agents are not typically recommended during pregnancy. Rhizoxin is an antimitotic agent with anti-tumor activity. Paclitaxel (Taxol) was a novel antimitotic agent that promoted microtubule assembly.