ACTA2 and idiopathic pulmonary fibrosis: It is critical to mention here that due to pathological variations between IPF lungs, it is important to validate, prior to drug screening, on at least 10 different primary IPF cultures that the selected cells respond (by decreasing the expression of fibrotic markers ACTA2, COL1A1) to currently approved drugs commonly used in IPF such as pirfenidone and nintedanib.