We also noticed that PRC1 was associated with EZH2-mediated H3K27me3, EZH2 was associated with EED, Dnmt1, and Dnmt3a, and EED was associated with NCoR, CoREST, and mSin3a at the COX-2 promoter in IPF, suggesting that COX-2 silencing in IPF could be mediated by PRC1 through blocking of transcriptional activation factor recruitment and preventing transcription initiation and that EZH2/EED may also lead to DNA methylation and histone deacetylation to reinforce epigenetic silencing of the COX-2 gene. This evidence concerns the gene PTGS2 and idiopathic pulmonary fibrosis.