Alternol inhibits OS cells proliferation and induces G2/M cell cycle arrest in human OS cells. (A) Human osteosarcoma cell line 143B, MG63, U2OS, KRIB cells were treated with vehicle (0.1% DMSO) or alternol (2.5, 5.0 and 7.5 μM) for 24 or 48 hrs, cell viability was measured by CCK8 assay. (B) Chemical structure of alternol. (C and D) Cell colony formation of 143B and MG63 treated with vehicle or alternol. (E) 143B and MG63 were treated with vehicle or alternol (2.5 and 5.0 μM) for 12 hrs, cell cycle was analysed using flow cytometry. (F) Cell cycle distribution presented as the mean ± S.D. from three independent experiments. (G and H) 143B and MG63 were treated with vehicle or alternol (2.5 and 5.0 μM) for 12 hrs, cell cycle proteins p21, p27, cyclinB1 and CDc2 expression were determined by western blot. *P < 0.05 versus with vehicle control, **P < 0.01 versus with vehicle control.