Fig. 7.

UV-B irradiation increases the level of MMP-2 via p38 activation. Human nonpigmented ciliary epithelial cells were cultured for 24 hr and then the cells pretreated with SB203580 (p38 inhibitor) were irradiated with UV-B at levels of 0, 50, 100, and 150 mJ/cm². Then, the cells were cultured for another 12 and 24 hr under serum-free culture conditions. (A) Cell/matrix layers were collected 10 min after UV irradiation and analyzed by Western blot against phosphor-p38. The level of phosphor-p38 treated with SB203580 was inhibited at the same level as the control (0 mJ/cm²). (B) Immunofluorescence showed that phosphor-p38 was labeled in the cells at 150 mJ/cm², but not in SB203580-treated cells. Cell/matrix layers were collected at 12 (C) and 24 (D) hours after UV irradiation and analyzed by ELISA. The active MMP-2 in the SB203580-treated cells was suppressed compared with the SB203580-untreated vehicle cells. The values for each control sample (0 mJ/cm²) without SB203580 were arbitrarily assigned a value of 1. The results represent the mean ± standard deviation of four independent determinations. **P < 0.05 versus control.