EXPERIMENTAL APPROACH
Lung CYP2A13, CYP2A6 and CYP2A7 (and CYP1A2) mRNA levels in smokers and non-smokers were assessed in Gene Expression Omnibus (GEO) datasets (GSE40364, GSE11874 and GSE103845). The impact of chronic twice daily subcutaneous nicotine at two doses (0.3 and 0.5 mg kg-1), versus vehicle, on lung CYP2A protein levels was assessed. The impact of ethanol self-administration was also investigated, with and without nicotine treatment.