YY1 and idiopathic pulmonary fibrosis: Moreover, in fibroblasts and idiopathic pulmonary fibrosis models, YY1 is regulated post-translationally by the E3 ubiquitin ligase NEDD4, which ubiquitinates YY1, alters its protein stability, and thereby modulates TAB1-dependent profibrotic proliferation and extracellular matrix production.