Interestingly, nicotine-mediated activation of both a5 and a9 nAChRs have been shown to upregulate PD-L1 expression in cancer cells via STAT3 signaling pathways (90, 93), so a positive correlation of nAChRs with PD-L1 may be expected (Supplementary Figure 2). The gene discussed is STAT3; the disease is cancer.