CDK4 and malignant colon neoplasm: Among cell cycle-related genes that we detested, the expression levels of cdc2, cdc25a, CDK2, CDK4, cyclin A2, cyclin B1, and cyclin D1 were elevated, and the expression level of p21 was reduced in HT-29 and Caco-2 with rhMMP1 treatment or TAMs-CM incubation, suggesting that MMP1 promoted cell cycle acceleration of colon cancer cells by activating cdc25a/CDK4-cyclin D1 and p21/cdc2-cyclin B1 complexes.