Figure 5.

sPLA₂-IIA-activated intracellular signaling cascades in cardiac fibroblasts (CFs) require HB-EGF shedding. (A) Cells were stimulated with 1 μg/mL of sPLA₂-IIA for the indicated times, and HB-EGF expression was determined by flow cytometry: untreated (solid black curves) and sPLA₂-IIA-treated (solid dark grey curves) CFs were compared with isotype controls (solid light grey curves). * p < 0.001, ** p < 0.01, and *** p < 0.5 vs. control cells; mean ± SD CFs were pretreated with the indicated inhibitors and then incubated with 1 μg/mL of sPLA₂-IIA: after 15 min, HB-EGF (B) and phospho-EGFR (C) expression were analysed by flow cytometry: untreated cells (open black curves) were compared with sPLA₂-IIA-treated cells in the absence (open dark grey curves) or presence of the indicated inhibitors (open blue curves). Solid light grey curves show isotype controls. (D) After 15 min, ERK, Akt, P70S6 and S6 phosphorylation were determined by immunoblotting. n = 3.