USP21 and colorectal carcinoma: An in vivo mouse MC38 (CRC cell line) subcutaneous transplantation tumor model and an azoxymethane (AOM)/dextran sodium sulfate (DSS)–induced spontaneous CRC model both confirmed that gallic acid can affect Foxp3 protein levels by targeting the expression of ubiquitin specific peptidase 21 (Usp21) in Tregs, inducing the formation of Th1-like Tregs and reducing their immunosuppressive function (170).