Fig. 5. Inhibition of spinal mitogen-activated protein kinases inhibited or reversed the increased expression of Fos protein by intrathecal injection of ephrinB1-Fc. Dimethyl sulfoxide (DMSO), 0.5 μg SB203580 (SB), 0.5 μg U0126 (U), or 0.5 μg SP600125 (SP) was intrathecally administrated at 30 min before intrathecal injection of ephrinB1-Fc (0.5 μg) in pretreatment experiment and at 30 min after intrathecal injection of ephrinB1-Fc (0.5 μg) in posttreatment experiment. Spinal Fos protein expression was assayed at 2 h after ephrinB1-Fc injection (see schematic illustration of experimental protocol in Fig. 4,A and Fig. 4 B ). (A , C ) The representative immunohistochemical staining, and (B , D ) the quantitative data of Fos expression in the spinal cord of mice in pretreatment experiments or posttreatment experiments. **P < 0.01 compared with DMSO + ephrinB1-Fc group or ephrinB1-Fc + DMSO group, n = 6 mice in each group, Scale bar = 100 μm.