Data and statistical analysis
The data and statistical analyses complied with the recommendations of
experimental design and analysis in pharmacology (Curtis et al., 2018).
The data were analyzed using GraphPad Prism version 7.1a. A p-value of
<0.05 was considered statistically significant.
GEO multiarray statistical
analysis
Nonparametric unpaired Mann-Whitney U-tests were used to test
differences in CYP2A13, CYP2A6 and CYP2A7 expression levels between
smokers and non-smokers in the small airway epithelium of the lung in
GEO datasets: GSE30063 and GSE108134.
For GSE11874, the D’Agostino-Pearson omnibus normality test was used to
determine the normality of signal distribution of CYP2A13, CYP2A6 and
CYP2A7 expression levels in smokers’ small airway epithelium of the
lung, followed by correlation analyses to assess the relationship
between CYP2A13, CYP2A6 and CYP2A7 expression levels and pack-year data,
within smokers.