TGFB1 and chronic obstructive pulmonary disease: Functional annotation clustering of these gene sets revealed that they are involved in multiple functional pathways involved in COPD pathogenesis, including TGFβ (transforming growth factor beta) signaling, immune cell trafficking, calcium signaling, phosphotadidylinositol signaling, actin cytoskeleton regulation, focal adhesion, cell-to-cell signaling, tight junction, mTOR (mammalian target of rapamycin) signaling, apoptosis, tissue remodeling, and wound repair pathways.