ACTA1 and idiopathic pulmonary fibrosis: The increased numbers of myofibroblasts found within IPF lungs occurs in part through the differentiation of resident fibroblasts (8); this involves reorganization of the actin cytoskeleton, increased expression of αSMA, and incorporation of actin stress fibers (9), a process regulated by the TGF-β1/Smad pathway (10, 11).