Inhibition of p38 mitogen activated protein kinase (MAPK) suppresses UVB-mediated induction of inflammatory cytokine production in human HaCaT keratinocytes.

<p>HaCaT cells were treated with the test substances (5 µM SB203580, 20 µM SP600125, or 40–200 µg/ml afzelin) after irradiation with 20 mJ/cm² UVB. <b>A.</b> After 12 h, cyclooxygenase (COX)-2 protein expression was assessed by Western blotting. The histogram depicting relative COX-2 protein expression levels was normalized to β-actin expression level. Representative data, n = 3 (A). <b>B.</b> Prostaglandin-E₂ (PGE₂)_,<b>C.</b> interleukin-6 (IL-6), and <b>D.</b> tumor necrosis factor-α (TNF-α) concentrations in cell culture supernatants from the same experiments. Data are means ± SD, n = 5 (B–D). ^§<i>P</i><0.01 compared with the vehicle-treated group, ^¶<i>P</i><0.01 compared with the UVB-treated group (B–D).