MMP12 and idiopathic pulmonary fibrosis: Lehmann hypothesized that the reprogramming of alveolar epithelial cells by SASP components—such as interleukin-6 (IL-6), interleukin-1β (IL-1β), matrix metalloproteinase-12 (MMP-12), chemokine ligand 2 (CCL2), and keratinocyte growth factor—plays a major role in the pathophysiology of IPF.