FAS and idiopathic pulmonary fibrosis: Both H3K9Me3 and H3K27Me3 marks are associated with gene silencing and have been implicated as drivers of other chromatin changes, including histone deacetylation and DNA methylation.26 Interestingly, we did not observe any difference in DNA methylation at the Fas gene promoter in fibrotic lung fibroblasts from mice or IPF patients, and it is unclear in this case what the exact relationship is between H3K9Me3 and histone deacetylation in regulating Fas expression in fibrotic lung fibroblasts.