AIM: To investigate the effects of KN-93, a CaMKⅡ selective inhibitor on cell proliferation and the expression of p53 or p21 protein in human hepatic stellate ceils.METHODS: Human hepatic stellate cells (LX-2) were incubated with various concentrations (0-50 μmol/L) of KN-93 or its inactive derivative, KN-92. Cell proliferation was measured by CCK-8 assay, and the expression of two cell cycle regulators, p53 and p21, was determined by SDS-PAGE and Western blotting.RESULTS: KN-93 (5-50 μmol/L) decreased the proliferation of human hepatic stellate cells in a dosedependent manner from 81.76% (81.76% + 2.58% vs 96.63% + 2.69%, P ＜ 0.05) to 27.15% (27.15% + 2.86% vs 96.59% + 2.44%, P ＜ 0.01) after 24 h treatment.Incubation of 10 μmol/L KN-93 induced the cell growth reduction in a time-dependent manner from 78.27% at 8 h to 11.48% at 48 h. However, KN-92, an inactive derivative of KN-93, did not inhibit cell proliferation effectively. Moreover, analysis of cell cycle regulator expression revealed that KN-93 rather than KN-92 reduced the expression of p53 and p21.CONCLUSION: KN-93 has potent inhibitory effect on proliferation of LX-2 cells by modulating the expression of two special cell cycle regulators, p53 and p21.