JNK acts downstream of Rho GTPases to promote Schwann cell migration. (A) Schwann cells were pretreated in the presence or absence of 10 μM SP600125 or 20 μM JNK inhibitor I and incubated with or without 20 ng/ml NRG1 in Boyden chambers (12 independent fields). (B and C) Schwann cells were stimulated with NRG1 for 0–120 min. The cell lysates were immunoblotted with an anti-(pThr¹⁸³/pTyr¹⁸⁵) JNK antibody that recognizes active JNK. The cell lysates were also immunoblotted with an anti-JNK antibody. The levels of phosphorylated forms were normalized to the amount of total JNK (n = 3). (D and E) JNK phosphorylation was measured at 0–360 min (n = 3). (F) Cells were pretreated with or without 2 ng/ml C. difficile Toxin B. After incubation with NRG1 for 120 min, JNK phosphorylation was assayed (n = 5). Error bars show ±SD. Data were evaluated by using one-way ANOVA (*, P < 0.01).