Objective: To investigate the mechanism of carcinogenesis, invasion and metastasis. Methods: The expressions of adhesive molecule and adhesive structure in v-k-ras transformed normal rat kidney cells (KNRK) were detected with a variety of molecular biological techniques, including cell culture, immunofluorescence labeling, electron microscopy, polyacrylamide gel electrophoresis, and protein blotting, and compared with normal rat kidney (NRK) cells. Results: The significantly shortened doubling time, remarkably active proliferation ability in soft agar, and invasive growth in the abdomen of nude rat, demonstrated the malignant biological behaviors of KNRK cells. In KNRK cells, the adhesive molecules, P-cadherin, α and β catenin, actin,and adhesive structures, the adhesive junction and gap junction, were all abnormally expressed. And cell aggregation was significantly decreased. The aggregation ability disappeared at 20℃, and became active with a suitable amount of calcium solution. Conclusion: Following the transfection of virus K-ras gene, normal cells were transformed into malignant cells. In early stage of cancer, the variation of adhesive ability may be one of the vital factors underlying tumorigenesis, invasion and metastasis.