Fig. 1.

Effect of interleukin (IL)-1β on matrix metalloproteinase (MMP)-9 activity in house ear institute-organ of Corti 1 (HEI-OC1) cells. IL-1β increases MMP-9 activity and mRNA expression. (A, B) HEI-OC1 cells were treated with various concentrations of IL-1β for 20 hours. Conditional media were collected after 20 hours and gelatin zymography was performed (A). The MMP-9 mRNA expression levels were determined by reverse transcription-polymerase chain reaction (RT-PCR). The levels of actin were used as a loading control (B). (C, D) HEI-OC1 cells were treated with the 1 ng/mL IL-1β for the indicated time periods. Conditional media were collected after 20 hours and gelatin zymography was performed (C). The MMP-9 mRNA expression levels were determined by RT-PCR. The levels of actin were used as a loading control. The values in (B, D) represent the mean±SD from three independent samples. ^*P<0.001 compared to the control. The data represent three independent experiments.