TGFB1 and breast carcinoma: For KPC3 tumors, the impaired tumor growth suppression after early TGF-β blockade was not immune mediated and could not be associated with impaired proliferation, but was associated with decreased intratumoral collagen disposition, as has also been observed in the murine mammary carcinoma 4T1 model and the human mammary carcinoma MDA-MB-231 model (37, 38).