TGFB1 and malignant colon neoplasm: In the microenvironment of multiple malignancies TGF-β1 has immune suppressive function, inhibiting the activation and proliferation of T cell, B cells and natural killer cells [31–33], which is also reminiscent of GARP’s regulatory function on TGF-β1 in the tumor microenvironment of breast cancer and colon cancer [18, 20].