Finally, pirfenidone led to significant downregulation of basal P53 gene expression in IPF-fibroblasts, but which was, as previously reported [31], paradoxically also observed in LBH589-treated cells (Fig 3O), despite upregulation of the p53 target genes CIP1 and PUMA. We do not have a plausible explanation for down-regulation of P53 mRNA expression in response to LBH589. This evidence concerns the gene TP53 and idiopathic pulmonary fibrosis.