COL1A1 and idiopathic pulmonary fibrosis: To validate the SOX9-driven profibrotic genes in IPF fibroblasts, we quantified transcripts using real-time PCR for ECM genes (COL1A1, COL3A1, COL14A1, COL15A1, and ACTA2) and proteoglycan-associated genes (ASPN, OGN, POSTN, and CTGF; Figure 3C).