S100A4 was originally labeled as a specific marker of fibroblasts in different tissues and was termed as FSP-1 (fibroblast-specific-protein-1), but further studies showed that S100A4 is also involved in the fibrogenic of mesenchymal progenitor cells in the lung thus contributing to the pathogenesis of IPF [77]. Here, S100A4 is linked to idiopathic pulmonary fibrosis.