Fig. 5.

The p38 mitogen-activated protein kinases (MAPK) signaling pathways play important roles in interleukin (IL)-1β-induced matrix metalloproteinase (MMP)-9 activity and mRNA expression in house ear institute-organ of Corti 1 (HEI-OC1) cells. IL-1β induces MMP-9 activity and mRNA expression via the p38 MAPK signaling. (A) HEI-OC1 cells were pretreated with 50 µM ERK inhibitor (PD98059), 10 µM p38 MAPK inhibitor (SB203580), and 20 µM JNK inhibitor (SP600125), and then stimulated with 1 ng/mL IL-1β for 20 hours. Conditional media were collected and gelatin zymography was performed (A). The MMP-9 mRNA expression levels were determined by reverse transcription-polymerase chain reaction. The levels of actin were used as a loading control. The values in (B) represent the mean±SD from three independent samples. ^*P<0.001 compared to IL-1β. The data represent three independent experiments.