FIGURE 8.

EGF together with ionomycin enhances iPLA₂γ activity. COS-1 cells were co-transfected with M1 GFP-iPLA₂γ WT and COX1. After 24 h COS-1 cells were incubated with EGF (100 ng/ml) and/or ionomycin (Iono, 1.0–1.5 μm) for 40 min. A, stimulation by EGF and ionomycin significantly increased PGE₂ release compared with unstimulated cells or cells stimulated with each agonist alone. *, p < 0.001 EGF + ionomycin versus untreated, p < 0.05 EGF + ionomycin versus ionomycin (alone), p < 0.001 EGF + ionomycin versus EGF (alone), four experiments. B, COS-1 cells were co-transfected with M1 GFP-iPLA₂γ WT and COX1. After 24 h 1 group of cells was preincubated with BEL (30 μm) for 6.5 h. Then cells were incubated for 30 min with EGF and ionomycin with or without BEL. The increase of PGE₂ release was inhibited almost completely in presence of BEL. *, p < 0.01 EGF + ionomycin versus untreated. *, p < 0.01 EGF + ionomycin versus EGF + ionomycin + BEL, 3 experiments. C, cell lysates were immunoblotted with antibodies to phospho-ERK (pERK) or tubulin. EGF and ionomycin enhanced phosphorylation of ERK.