An analogue of the sponge-derived anti-microtubule tripeptide hemiasterlin with antimitotic and potential antineoplastic activities. Hemiasterlin analogue E7974 binds to the Vinca domain on tubulin, resulting in inhibition of tubulin polymerization and microtubule assembly; depolymerization of exsiting microtubules; inhibition of mitosis; and inhibition of cellular proliferation. This agent may have more affinity for the beta-3 tubulin isotype.