Differentially expressed genes in the lungs of the of the tobacco smoke (TS)-, crystalline silica (CS)-, and TS plus CS-exposed rats. Global gene expression profiles in the rat lungs were determined by next generation sequence analysis as described in the text. Significantly differentially expressed genes (SDEGs) are those with a fold change > 1.5 and an adjusted p value < .05 compared with the control (air) group. A, The number of total, upregulated, and downregulated SDEGs in each exposure group of the rats compared with the control group. B, Venn diagram of the SDEGs showing the number of unique and overlapping genes in each exposure group.