HDAC9 and idiopathic pulmonary fibrosis: To further confirm the reduction of nuclear HDAC activity in IPF, we analyzed fractions containing HDAC1 and HDAC2 by IP assays of endogenous proteins using antibodies specific for pan-acetylated lysine (AcK) or phosphorylated serine (PhS) and subsequent WB analysis of precipitated proteins using HDAC1- or HDAC2-specific antibodies (Fig. 5d).