Albumin-induced increase in matrix metalloproteinase (MMP)-9 is dependent on the activation of mitogen-activated protein kinase (MAPK) pathways. (a) Representative western blot shows that treatment with BSA for 90 minutes induced an increase in the level of phosphorylated p38 MAPK, extracellular signal regulated protein kinase (ERK) and c-Jun N-terminal kinase (JNK). Representative zymogram and corresponding quantification of the level of MMP-9 release by astrocytes treated with albumin in the presence (+) or absence (−) of (b) the p38 MAPK inhibitor SB203580, (c) the ERK pathway inhibitor PD98059, and (d) the JNK inhibitor SP600125. Inhibition of the p38 MAPK and ERK pathways significantly suppressed the release of MMP-9 induced by albumin. whereas inhibition of JNK pathway did not modify the response to albumin. Data are representative of mean ± SEM of three independent experiments. **P < 0.01, ***P < 0.001 compared with the BSA-treated group.