AIM: To observe the growth inhibitory effect of wild-type Krasl gene on a colonic adenocarcinoma cell line Caco-2.METHODS: Recombinant plasmid pCI-neo-Kras2 with wild type Krasl open reading frame was constructed. The Caco-2 cells were transfected with either pCI-neo or pCl-neo-Kras2 using Lipofectamine 2000. The expression of wild type Krasl was examined by Northern blot analysis. And the expression of wild type Kras2 protein was examined by Western blot analysis. The effects of wild-type Krasl on cell proliferation were analyzed by monotetrazolium (MTT) assay, meanwhile analyses of cell cycle and spontaneous apoptosis rate were carried out by flow cytometry (FCM).RESULTS: The plasmid of pCl-neo-Kras2 was successfully established. The growth rate of cells transfected with pCl-neo-Kras2 was significantly lower than the control cells transfected with the empty pCI-neo vector (P < 0.05). Cell cycle analysis revealed arrest of the pCI-neo-Kras2 transfected cells in Go/G1 phases, decreased DNA synthesis and decreased fractions of cells in S phase. The proliferative index of cells transfected with pCI-neo-Kras2 was decreased compared with the control cells (49.78% vs 64.21%), while the apoptotic rate of Caco-2 cells with stable Krasl expression increased (0.30% vs 0.02%).CONCLUSION: The wild-type Krasl gene effectively inhibits the growth of the colonic adenocarcinoma cell line Caco-2.