TGFB1 and neoplasm: ECM production within the tumor is upregulated, resulting in most cases in enhanced stiffness compared to healthy tissue.81 This higher matrix stiffness, correlated with more densely packed ECM fibers, presents two problems: first, increased stiffness can promote metastatic behavior in cancer cells,82 and second, delivery of drugs and perhaps immune cells throughout the entirety of the tumor is hindered.83 TGF-β inhibitors, for example, reduce the secretion of ECM proteins84 in order to prevent further ECM alterations.