Treatment with a specific PDGFR inhibitor (PDGFR V Furuta et al., 2006) at the nanomolar range (10 nM) did confirm the PDGFR-dependency of this effect of IPF fibroblast-derived ECM on PRRX1a and –1b mRNA levels in control fibroblasts (Figure 3E). The gene discussed is PDGFRB; the disease is idiopathic pulmonary fibrosis.