TGFB1 and fibrosis: Mouse PCLS were exposed to either 10 μM nicotine, 10% cigarette smoke extract (CSE), or a fibrosis-inducing cocktail (FC) containing TGF-β, PDGF-BB, TNF-α, and LPA, which are known mediators of lung fibrosis (Jensen et al., 2012; Alsafadi et al., 2017; Song et al., 2019).