THY1 and pulmonary fibrosis: Thy-1+ lung fibroblasts are considered progenitors of lung myofibroblasts in patients with idiopathic pulmonary fibrosis (IPF)50, but Thy-1 expression is silenced epigenetically in IPF-derived myofibroblasts51, suggesting that Thy-1 expression is not required for the maintenance of myofibroblast differentiation in IPF.