·AIM:To investigate the inhibitory effect of transforming growth factor(TGF)-β2 on the proliferation of human corneal endothelial cells(HCEC)in vitro,and its cellular and molecular mechanisms.·METHODS:Synchronized HCEC,prepared from in vitro cultured HCEC line by serum-starvation,were treated with TGF-β2 at different concentration for different time duration,respectively.After HCEC treated with TGF-β2,the inhibitory effect of proliferation,phase status in cell cycle,and expression of p27kip1 and p21cip1 of HCEC was examined by methods of cell number counting,MTT staining,flow cytometry(FCM)and realtime PCR,respectively.·RESULTS:TGF-β2 at the concentration of 1-15μg/L had obvious inhibitory effects on HCEC proliferation in dose-and time-dependent manner,9μg/L was the peak concentration of TGF-β2 for inhibiting HCEC cell proliferation.After treated with 9μg/L TGF-β2,the population of HCEC in G1/G0 phase increased obviously in time-dependent manner.After HCEC treated with 9μg/L TGF-β2,the expression of p27kip1 increased obviously after 24 hours,and expression of p27kip1 and p21cip1 increased obviously 48 hours later in time-dependent manner.·CONCLUSION:TGF-β2 has obvious inhibitory effect on HCEC proliferation,and the inhibition is in dose-and time-dependent manner.The mechanism of TGF-β2 inhibition is most probably accomplished by inducing the in turn expression of p27kip1 and p21cip1 which keep HCEC rest on G1/G0 phase.·