CCND1 and colorectal cancer: To further delineate the molecular mechanism responsible for MG53-induced downregulation of cyclin D1, we first overexpressed MG53 in HCT116 and AGS cells and observed dose-dependent decreases of cyclin D1 at the protein level (Fig. 3a, b), while shRNA-mediated inhibition of MG53 markedly increased cyclin D1 in the HCT116 and SW480 colorectal cancer cells (Fig. 3c, d).