S100A4 and idiopathic pulmonary fibrosis: To confirm the relevance of fibroblast-derived S100A4 in human fibrotic lung disease, we demonstrate that S100A4 is upregulated in IPF-patient-derived fibroblasts, both at the mRNA (increased 3-fold, p < 0.001) and protein levels (>5-fold, p < 0.001) (Fig. 10, A and B).