CD4 and neoplasm: CAFs can impede the proliferation of effector T cells and recruit CD4+ CD25+ T cells to the tumor stroma by secreting CXC chemokine ligand 12, and this recruitment leads to the transformation of CD4+ CD25+ T cells into CD25+ forkhead box protein 3+ T cells, inducing immunosuppression and drug resistance within the TME of TNBC.