<正> Using the transfection technique, P151NK4b' was introduced into P151NK4b gene deleted humanmelanoma A375 cells, and a cell model MLIK6 overexpressing P15 ' was constructed. Comparing with the control cells MLC2, MLIK6 cells in G1 phase increased by 11% , but those in S phase decreased by 15% by KCM. By the method of thymidine (TdR) and N2O arresting, the proportions of synchronized M phase cells of MLIK6 and MLC2 were measured and found to be 89.1 % and 76 .8 % , respectively, and the cells in G, phase were 74.3 % for M LI K6 and 76. 4% for MLC2. The result of 3H-TdR incorporation indicated that the transition of G1/S of MLIK6 cell was delayed 2 h as compared with that of MLC2 cells, and incorporation rate also decreased. The observation on expressions of some G1/ S-related relatory regulating genes showed that in MLIK6 cells the protein level of P27KIPI increased with the decreasing expressions of oyclinD1, cyclinE and c-myc, especially cyclinD1 in late G1 phase. The expression of cyolinE obviously dec
