Inhibition of NADPH oxidase activity reduces the cellular proliferation and invasiveness of p38α-deficient A431 SCC keratinocytes.

<p>(A) p38α downregulation increases NADPH oxidase activity and generates intracellular ROS. Intracellular ROS levels were measured using a cell-permeable fluorogenic probe, 2′,7′-dichlorofluorescein diacetate (DCFDA) dye, which detects hydrogen peroxide production, following siRNA-mediated p38α knockdown in A431 cells. NOX2 levels were assessed by Western blotting in extracts prepared from p38α knockdown (p38αKD) A431 cells. NADPH oxidase activity was determined as previously described <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097245#pone.0097245-Rezvani2" target="_blank">[11]</a>. scr, scrambled control siRNA. Presence of NADPH oxidase inhibitor, DPI (2.5 µM), inhibits the proliferation (B) and cellular invasiveness (C) of A431 cells treated with SB203580 or p38αKD A431 cells. Proliferation was measured by a BrdU incorporation assay, and invasiveness was assessed in matrigel-coated chambers. Each histogram represents results from triplicate cultures; *<i>p</i><0.05.