Dihydrocytochalasin B (DCB) is a member of the cytochalasin mycotoxin family that inhibits actin assembly. It blocks cleavage furrow formation and cytokinesis in synchronous HeLa cells at a concentration of 10 μM. DCB induces tetraploidy and arrests the cell cycle indefinitely in the G1 phase in REF-52 cells.It also increases the drug sensitivity of multidrug resistant SKVLB1 cells to paclitaxel and doxorubicin in vitro.