KITLG and major depressive disorder: We did not detect differences in protein levels between MDD and BD patients at baseline (BDNF p = 0.42; proBDNF p = 0.21; mBDNF p = 0.27; rBDNF p = 0.37; EGF p = 0.98; MIF p = 0.79; SCF p = 0.61).