IFNG and psoriasis: JAK inhibition by tofacitinib strongly reduces clinical signs of psoriasis, and, potently blocks signaling through the common γ chain-containing receptors, including IL-2, IL-4, IL-7, IL-9, and IL-15, or through canonical receptors for cytokines, such as IFN-γ, IL-21, IL-6, and to a lesser extent, IL-12 and IL-23 [22].