TGFB1 and colon carcinoma: This, and another study of colon carcinomas [17], concluded that TGFβ signaling within cancer-associated fibroblasts (CAFs) forms a barrier to intra-tumoral penetration of immune cells that can be alleviated by blockade of TGFβ signaling, resulting in synergy between α-PDL-1 and α-TGFβ therapy.