Interestingly, treatment of IPF fibroblasts with the EP300 inhibitor CBP3043 (EP300inh; Supplementary Fig. 7a) reconstituted the HDAC activity to levels similar to Ctrl fibroblasts, supporting the causal involvement of actEP300 during the inactivation of HDAC1 in IPF. This evidence concerns the gene HDAC9 and idiopathic pulmonary fibrosis.