Effects of the epipodophyllotoxin derivative VM 26 in mitosis and in interphase.

The epipodophyllotoxin derivative VM 26 inhibits entry of mouse mastocytoma cells into mitosis in cell cultures at drug concentrations of 0.01--1 microgram/ml, the cells being arrested in G2 phase of the cell cycle. At higher concentrations, the compound exhibits spindle poison activity which manifests itself in a shortlasting rise in the number of cells arrested in metaphase of mitosis. These cells then disintegrate after a short period of time.