Azaspirane enhances the growth inhibitory effect of conventional chemotherapeutic agents. MM.1S cells were cultured with control media (□) and with 0.6 μM (▦) or 1.25 μM (▪) azaspirane in the absence or presence of Dex (0.5 μM), Dox (0.5 μM), and As₂O₃ (1 μM) for 24 hours. Cell growth was assessed by MTT assay, and data represent mean (± SD) of quadruplicate cultures. ^*P < .01.