FIGURE 4.

TBH does not inhibit the proteasome, nor does it stimulate IL-8 production. ARPE-19 cells were cultured in serum-, pyruvate-, and phenol red-free DMEM in the presence of different concentrations of TBH for 1 h. The chymotrypsin-like activity of the proteasome was determined (panel A). After recovery in normal medium for 8 h, levels of mRNA for IL-8 were assessed by real-time RT-PCR analysis (panel B) and IL-8 concentrations in the medium were determined by ELISA (panel C). The results are the mean ± S.D. of three independent experiments. Asterisk indicates p < 0.05.