S100A4 and idiopathic pulmonary fibrosis: Increased expression levels of S100A4 have been reported in the lungs of IPF patients, including in mesenchymal progenitor cells, suggesting the involvement of S100A4 in IPF pathogenesis through modulating mesenchymal progenitor cell fibrogenicity (Xia et al., 2017; Lee et al., 2020).