Interestingly, it was reported, several years ago, that alterations in specific nAChR subunits, including α3, α4, α5, β2, and β4, contribute to smoking addition and lung cancer [78,79,80]; these findings were obtained in genome-wide association studies that found single-nucleotide polymorphisms in gene clusters that code for the genes for these nAChR subunits. Here, CHRNA4 is linked to lung cancer.