TGFB1 and pancreatic adenocarcinoma: The previous study has also demonstrated that once PAAD cells met COL1A1, Snail expression conducted by the increasing of TGF-β1 (Transforming Growth Factor- β1) signaling would begin, which in turn accelerate the progress of PAAD invasion by the upregulated MT1-MMP (membrane type 1-MMP) expression (24).