To assess the potential role of CYPJ in the regulation of cell cycle, we examined and compared cell distribution of human hepatic cancer cell line SK-Hep1 cells transfected with empty vector pCMV-HA, cells overexpressing either CYPJ or PPIase-impaired CYPJ mutant from pCMV-CYPJ or pCMV-CYPJ(R44A&F49A) respectively, cells with CYPJ knockdown by CYPJ-siRNAs and inhibition of CYPJ PPIase activity by CsA. The gene discussed is PPIL1; the disease is liver cancer.