XRCC6 and idiopathic pulmonary fibrosis: Indeed, following CMH exposure (30 μM, 72 h), IPF-lung myofibroblasts although keeping stable SIRT1 expression levels (not shown), they show an affected activity of SIRT1, as indicated by the increased acetylation of Ku70, a SIRT1 nonhistone substrate [23,25,29], from an optical density ratio (OD) of 2.43 to 5.6 in pan-acetyl immunoblots (IB) of Ku70 immunoprecipitate (IP) (Figure 1D).