MAPK3 and major depressive disorder: Subjects with MDD showed an increased expression of the activated (phosphorylated) forms of the extracellular signal-regulated kinases (ERK)1/2 (+ 22%, t = 2.293, p = 0.03) and the c-Jun N-terminal kinases (JNK) (+ 56%, t = 2.468, p = 0.02) but not the p38 MAPK (+ 19%, t = 1.317, p = 0.19) compared with matched controls (Fig. 2a, c).