HDAC1 and idiopathic pulmonary fibrosis: We have determined the enzymatic activity of HDACs in the nucleus, as well as HDAC1-specific enzymatic activity in the nucleus and cytosol of human primary fibroblasts from Ctrl and IPF patients, whereas the other reports neither discriminated between the cytosolic and nuclear fractions of cells used, nor directly determined the enzymatic activity stage of the HDACs.