Finally, the fundamental difference between the effects of LBH589 and pirfenidone was, that LBH589-treatment resulted in cell cycle arrest and induction of apoptosis in IPF-fibroblasts, as indicated by induction of p53/p21 and several apoptosis-inducing pathways, including survivin-suppression and ER stress-mediated apoptosis involving CHOP and the mitochondrial apoptotic pathway, whereas pirfenidone did not exert such responses. This evidence concerns the gene DDIT3 and idiopathic pulmonary fibrosis.