Figure 1. CAP induces TAK1 activation. A: TRPV1-induced TAK1 and JNK1 phosphorylation. CAP (20 µM) in scrambled shRNA HCEC subline caused time-dependent changes in TAK1 (left) and JNK1 (right) phosphorylation as revealed by western blot analysis. TAK1 expression level invariance validates protein loading equivalence. Results shown are representative of three independent experiments. B: Inhibition of TAK1 phosphorylation. Preincubation of scrambled shRNA subline for 60 min with either CPZ (10 µM) or 5z-OX (0.1 µM) suppressed CAP (20 µM)-induced TAK1 activation. TAK1 expression level invariance validates protein loading equivalence. C: Dose-dependent inhibitory effects of 5z-OX on TAK1 and MAPK phosphorylation. Scrambled shRNA subline was preincubated with 5z-OX (0.01–1.0 µM) for 1 h before exposure to CAP (20 µM) for 5 min. JNK1/2 expression level invariance validates protein loading equivalence. D: Dependence of IL-6 and IL-8 increases on TRPV1 and TAK1 activation. ELISA was performed after 24 h in presence or absence of CAP (20 µM). Each experiment was performed three times using triplicate samples. Results are expressed in pg/mg protein. Following 60 min exposure to CPZ (10 µM) or 5z-OX (0.1 µM), the effects of CAP (20 µM) were determined on the release of IL-6 and IL-8.