SMAD3 and nasopharyngeal carcinoma: Furthermore, our previous study has revealed that enrichment of TGF-β1 in NPC microenvironment promotes immune escape by inducing chemotactic migration of Regulatory T (Treg) cells to remodel the inhibitory immune microenvironment via the TGF-β1-SMAD3-PI3K-AKT-c-JUN-miR-200a-CXCL12-CXCR4 axis (21, 22).