Functional annotation clustering analysis demonstrated that genes falling into categories associated with cytokine signaling, including “Innate Immunity,” “Epstein-Barr virus infection,” “NF-κB signaling,” “guanylate-binding protein,” and “Chemokine signaling” were enriched in the NOS2+ human islet endocrine cells compared to the NOS2− cells (Figure 4C and D). Here, NOS2 is linked to Epstein-Barr virus infection.