Fig. 6. Phosphorylation of cPLA₂ at Ser505. (A) Immunocytochemistry with antibody to cPLA₂ phosphorylated at Ser505 and to calbindin D. Treatment with 200 nM PMA for 20 minutes triggered marked phosphorylation of cPLA₂, whereas stimulation with glutamate-receptor agonists alone (100 µM glutamate or 30 µM AMPA for 3 minutes) had little effect. Pre-treatment with 10 µM U0126 for 30 minutes completely blocked the phosphorylation of cPLA₂ that was induced by the combination of PMA and AMPA. Scale bar: 10 µm. (B) Quantification of experiments. The average fluorescence intensity of phosphorylated cPLA₂ in proximal dendrites after treatment with glutamate-receptor agonists and/or PMA was calculated. The values are means ± s.e.m. (n=13-30 for each condition). ^***P<0.001.