ACTA2 and idiopathic pulmonary fibrosis: For instance, in a study that examined the gene expression profile of explanted lungs from biopsy-proven cases of clinical diagnosis of IPF and non-specific interstitial pneumonia (NSIP), insulin-like growth factor binding protein (IGFBP)-5 and 6, Mucin 5B, and actin alpha 2 (ACTA-2) were specific for IPF.41