Albumin-induced increase in matrix metalloproteinase (MMP)-9 occurs independently of the transforming growth factor (TGF)-β receptor. Representative zymogram and corresponding quantification of the level of MMP-9 release by astrocytes treated with BSA in the presence (+) or absence (−) of (a) the TGF-β receptor I inhibitor SB431542, or (b) the Smad pathway inhibitor SIS3; neither inhibition of the TGF-β receptor I inhibitor nor the Smad pathway inhibited albumin-induced increase in MMP-9. (c) Representative zymogram of the level of MMP-9 release by astrocytes treated with BSA and TGF-β1 (10 ng/mL). Data are representative of mean ± SEM of three independent experiments. ***P < 0.001 compared with the BSA-treated group.