Similarly, expression of the AHRR gene, which also depends on AHR activation and consequent transcription activity [35], was significantly higher in synovial tissues from RA patients who smoked when compared to non-smokers (1.79 ± 0.48 vs. 0.53 ± 0.21 ng RNA, P = 0.036); this was not the case in nodule tissues (4.82 ± 3.41 vs. 1.78 ± 0.95 ng RNA respectively, Figure 1D). This evidence concerns the gene AHRR and rheumatoid arthritis.