Cytochalasin B is a cell-permeable mycotoxin. It inhibits cytoplasmic division by blocking the formation of contractile microfilaments. It inhibits cell movement and induces nuclear extrusion. Cytochalasin B shortens actin filaments by blocking monomer addition at the fast-growing end of polymers. Cytochalasin B inhibits glucose transport and platelet aggregation. It blocks adenosine-induced apoptotic body formation without affecting activation of endogenous ADP-ribosylation in leukemia HL-60 cells. It is also used in cloning through nuclear transfer. Here enucleated recipient cells are treated with Hoechst stain containing cytochalsin B. Cytochalasin B makes the walls of the oocytes smoother and makes it easy for micro-manipulation so that the zona pellucida is not so rigid and can be easily pierced by the micro-needles.