TGFB1 and malignant colon neoplasm: The ACVR2/TGFBR2/SMAD4 wild type microsatellite stable colon cancer cell line FET and ACVR2/TGFBR2 wild type/SMAD4-null SW480 colon cancer cells were treated with either activin or TGFβ and cellular growth was assessed.