ITGB3 and major depressive disorder: The lower ITGB3 expression observed here in MDD compared with control PBMCs is of particular interest because chronic (21 days) paroxetine treatment of LCLs has been demonstrated to increase the ITGB3 expression by nearly twofold.17 Further investigation of PBMC gene expression levels following antidepressant treatment in different MDD patient groups is vital for uncovering the role of ITGB3 in the mode of action of SSRI antidepressants and the utility of PBMC ITGB3 expression level as a MDD biomarker.