TGFB1 and neoplasm: Further, CD4+ T cells cultured in the presence of B7x+ tumor cells expressed Foxp3 at greater rates than those cultured with B7x- tumor cells, consistent with our in vivo findings (Fig. 2e), and this effect was diminished by the addition of anti-TGFβ1 blocking antibody into the culture (Supplementary Fig. 3a).