Cytochalasin D is an actin inhibitor, the removal of actin stress fibers is crucial for the chondrogenic differentiation. It may be an inhibitor of some fertilization processes such as sperm penetration or sperm head decondensation. Cytochalasin D inhibits CT26 tumor growth potentially through inhibition of cell proliferation, induction of cell apoptosis and suppression of tumor angiogenesis; it stimulates the expression of TF in B16 melanoma cells, activating both coagulation-dependent and -independent pathways via binding to FVIIa, eventually promoting lung metastasis. Cytochalasin D is also an inhibitor of microfilament-dependent phagocytosis, it (0.5 or 1.0 micrograms/ml) can inhibit intracellular multiplication of L. pneumophila in U937 monocytes. Cytochalasin D inhibits smooth muscle contraction by directly inhibiting contractile apparatus.