Genistein arrests cell cycle progression of A549 cells at the G(2)/M phase and depolymerizes interphase microtubules through binding to a unique site of tubulin.

Genistein (4',5,7-trihydroxyisoflavone), an isoflavone, is a major constituent of soyfoods. It has potential antiproliferative activity against several tumor types. We have examined the effect of genistein on cellular microtubules as well as its binding with purified tubulin in vitro.