IL9 and major depressive disorder: Among these inflammatory factors, insulin, HGF, NT-4, VEGF R2, IL-2 Rb, CD40L, VCAM-1, MCP-4, MIP-1b and IL-9 were also found altered in MDD patients in previous studies (11–19), while SCF R, ANG1, Fas, IGF-1R, Flt-3 L, ErbB3, LIGHT, IL-10 Rb, IL-21 and IL-28A was firstly found to have abnormal levels in MDD patients as compared to healthy controls.