Indeed, recent examination of idiopathic pulmonary fibrosis lung tissue identified induction of collagen-modifying enzymes that contribute to collagen cross-linking, including lysyl hydroxylase 2, but not increased collagen synthesis, as a defining feature of lung fibrosis that increases tissue stiffness and promotes fibrotic progression (37, 38). This evidence concerns the gene PLOD2 and idiopathic pulmonary fibrosis.