FN1 and neoplasm: 116,137 Instead, Fn ED-B is found in the tumor stroma72 and in the tumor vasculature.19 This splice variant of Fn has been found to enhance cell adhesion and formation of focal adhesions for cell spreading.56 ECM stiffening, a hallmark of cancer, has been found to enhance ED-B splicing of Fn to propagate a tumorigenic phenotype.13 Thus, changes in conformation, mechanics, and alternative splicing of Fn synergistically regulate tumorigenesis.