WT1 and idiopathic pulmonary fibrosis: The presence of calretinin and mesothelin (markers of mesothelial cells) (Mubarak et al., 2012) and Wt-1 expressing PMCs (Zolak et al., 2013) was recently demonstrated in parenchymal cells of explanted lung tissues from 16 patients with IPF supporting a role for PMC differentiation and their trafficking into the lung as contributors to the myofibroblast population in lung fibrosis.