Though this supports an anti-tumor role for B cells and antibodies, other studies have associated them with poor prognostic factors in breast cancer because human breast cancer cells can induce a regulatory phenotype in B cells, initiating the production of the transforming growth factor beta (TGF-beta), a cytokine that stimulates CD4 + T cells to become immunosuppressive T regulatory cells [19]. This evidence concerns the gene CD4 and breast cancer.