CD4 and neoplasm: Since TGF-β produced by tumor tissues facilitates the transformation of immature CD4+ T lymphocytes into FOXP3 Tregs in TME and activates NF-κB and Smad signaling pathways to induce FOXP3 expression, we highly hypothesize EGCG reduces the number of Treg subpopulation through downregulating TGF-β/Smad expression and blocking NF-κB activity based on the previous relevant research (70, 80–82).