Key signalling molecules and pathways involved in RV induced inflammatory responses in COPD pBECs. Genes that were identified to play a role in innate immune signalling that were increased in RV infected COPD pBECs include IRAK2, PELI1, CH25H, PMAIP1, ATF3 and GBP4. IRAK2, PELI1 and CH25H (bolded in box) are involved in signal transduction downstream of IL-1/TLR leading to NF-κB activation and production of inflammatory cytokines. Induction of PMAIP1, a mitochondria-associated protein, leads to apoptosis. ATF3 senses cellular stress and functions to reduce TLR4-mediated NF-κB signalling. GBP4 is an IFN-inducible GTPase that has been shown to disrupt IRF7 activation, thereby inhibiting the induction of type I IFNs. Solid line indicates up-regulation, and dashed line indicates down-regulation.