Multiple E3 ubiquitin-protein ligase genes, including RNF168, TRIM37, RNF40, and HUWE1, as well as the deubiquitinase BAP1 were upregulated in IPF AT1 cells, implicating the histone ubiquitination pathway which has been linked to double-stranded DNA break repair as well as transcription repression and activation (44). This evidence concerns the gene RNF40 and idiopathic pulmonary fibrosis.