GRIK4 and major depressive disorder: Of thirteen depression‐associated DRPs, seven proteins including DDC, FGFR2, KIBRA, MED22, OLIG1, RAI1, SLIT2 were upregulated, whereas six proteins including COX3, CRHBP, CSMD1, FSTL1, GRIK4, and LMTK3 were downregulated (Figure 6B).