Studies have shown that there is a reduced infiltration and activation of T cells in MSS/pMMR CRC, while the levels of immune suppressive cells (such as Tregs and myeloid-derived suppressor cells (MDSCs)) and immune inhibitory molecules (such as IDO1 and transforming growth factor-beta (TGF-β)) are elevated (48–50). The gene discussed is TGFB1; the disease is colorectal carcinoma.