Fig. 4.

Expression levels of selected immune/interferon response, stress/chemical response, mitochondrion, and smoking-associated genes by HIV status and smoking. Boxplots of normalized gene expression levels for selected genes upregulated in HIV+ smokers compared with HIV− non-smokers. Horizontal bars denote medians, boxes span IQRs, whiskers extend to 1.5 × IQR. Dots denote expression values from individual arrays. Probe intensities were normalized and generalized-log₂ transformed using the R/Bioconductor vsn package. Groups were compared using the Wilcoxon rank-sum test. IQR, interquartile range; TS+, tobacco smoker; TS−, non-smoker