ACTA1 and idiopathic pulmonary fibrosis: We first demonstrated that IPF patient-derived LFs cocultured with ADSCs decreased fibrotic factors, including collagen type I, type III, and α-SMA, and induced PTPRR expression, which led to the dephosphorylation of ERK1/2, one of the most important signaling cascades among the MAPK signal transduction pathways [31].