TGFB1 and cancer: However, in a mouse breast cancer model, increased level of TGFβ1 was associated with extensive deposition of type I collagen (Col-I) and pulmonary fibrosis, and then with activation of β1-integrin signaling and induction of the dormant-to-proliferative switch of DTCs (87), suggesting that TGFβ1 may play an opposite role in cancer dormancy, compared with TGFβ2.