TGM2 and breast cancer: However, in cells, there are many similarities in the progression between breast and ovarian cancer, e.g., the levels of both lysyl oxidase 1 (LOX1), a collagen-crosslinking enzyme that is crucial for matrix stiffness in breast cancer [22], and tissue transglutaminase (TG2), which also promotes ECM polymerization and crosslinking [23], are increased in ovarian cancer.