In RBA-1 cells, JEV induced MMP-9 expression and promoter activity, which was inhibited by pretreatment with inhibitors of NADPH oxidase (diphenylene iodonium chloride or apocynin), MAPKs (U0126, SB203580 or SP600125) and a ROS scavenger (N-acetylcysteine), or transfection with siRNAs of p47(phox) , ERK1, JNK2 and p38