STAT4 and treatment resistant depression: Gene expression profile associated with TRD included six genes three of them, PDGFA, EP300, and TGF-β1 were down-regulated (P-values: <0.0318, <0.0275 and <0.0194; respectively), while PRKRIR, TRAF6, and STAT4, genes were up-regulated (P-value <0.0439, <0.0142, <0.0082; respectively) (Table 3).