Cyclophilin A (CypA) is found to be highly expressed in different kinds of tumor cells,which could regulate the occurrence and development of many kinds of tumor through multiple signal transduction pathways such as inducing the formation of inflammatory carcinoma,accelerating the transcription cycle of tumor cells,promoting the invasion and metastasis of tumor cells,inhibiting the apoptosis of tumor cells and reducing the sensitivity of tumor cells to chemotherapy drugs.It suggests that CypA might be considered as a kind of oncogene,which is expected to be a novel target for tumor treatment.