It is well established that nicotine exerts its biological action via binding to nAChRs; however, nicotine signaling has also been reported to trigger the production of β-AR ligands, such as adrenaline and noradrenaline, which in turn stimulate β-ARs, contributing to cell growth, proliferation, and the development of lung cancer [7,23]. This evidence concerns the gene ADRB2 and lung cancer.