Morphological changes and anti-proliferation effects after isochaihulactone treatment of prostate cancer cells. (A) Human prostate cancer cell lines DU-145, PC-3, LNCaP were treated with isochaihulactone from 6.25 to 50 μM at 48 h and analyzed with the MTT assay. LNCaP cells were treated with 0.2% DMSO as a control (B) or 20 μM isochaihulactone (C) for 24 h. LNCaP cells were treated with increasing concentration of isochaihulactone from 3.125 to 50 μM at various times from 24 to 72 h and analyzed with the MTT assay (D). The data represent the means ± S.D. from three independent experiments. **, P < 0.01 versus vehicle.