<i>A. hydrophila</i>-induced ERK 1/2 phosphorylation is PKA mediated and is pro-apoptotic in HKM.

<p>(A) HKM were transfected with PKACA-siRNA, scrambled siRNA or pre-treated with H-89, U 0126 then infected with <i>A. hydrophila</i> and checked for total ERK and pERK activity 24 h p.i. using EIA based kits. HKM were pre-treated with or without U 0126 then infected with <i>A. hydrophila</i> and checked for (B) Hoechst 33342 positive cells and caspase-3 activity and (C) AV-PI staining 24 h p.i. Vertical bars represent mean ± SE (n = 6). <b>*</b>P<0.05, compared to HKM; <b>^γ</b>P<0.05, compared to HKM+Sc; <b>^#</b>P<0.05, compared to HKM+B; <b>^±</b>P<0.05, compared to HKM+Sc+B. HKM, control head kidney macrophage; HKM+Sc, HKM transfected with scrambled siRNA; HKM+B, HKM infected with <i>A. hydrophila</i>; HKM+Sc+B, HKM transfected with scrambled siRNA infected with <i>A. hydrophila</i>; HKM+PKACA-siRNA+B, HKM transfected with PKACA-siRNA infected with <i>A. hydrophila</i>; HKM+H-89+B, HKM pre-treated with H-89 infected with <i>A. hydrophila</i>; HKM+U 0126+B, HKM pre-treated with U 0126 infected with <i>A. hydrophila</i>.