To further explore existing evidence that some proinflammatory cytokines (e.g., TNFα and IL1β)7, 8, 9, 10 can modulate SERT activity, we tested the hypothesis that IL6-dependent activation of the STAT3 canonical inflammatory signaling11 exerts direct regulatory control over SERT expression, function and depression-like behavior. This evidence concerns the gene IL6 and major depressive disorder.