MMP12 and pulmonary fibrosis: In antibody-mediated Fas-induced lung fibrosis, mmp12-null mice have lower expression of profibrotic genes cry61 (a cysteine-rich ECM protein implicated in fibroblast adherence to ECM) and egr1 (early growth response factor-1; a zinc-finger transcription factor involved in pulmonary responses to TGF-β1) when compared to WT mice.