TGFB1 and cancer: Ye et al. [38] demonstrated that repression of TGFβ activity by transfection of dominant negative (DN) TGFβRII was sufficient to lead to vigorous tumor growth by FET cells in subcutaneous implants; however, as with FETα cell induced tumors FETDNRII orthotopic implants without ectopic TGFα expression resulted in invasive primary cancers that rarely metastasized.