Activation of MAPK following reperfusion is cPLA2α-dependent. A: The relative expression of phosphorylated p38 MAPK (P-p38) was measured in cPLA2α+/+ and cPLA2α-/- after MCAO and 6 hours of reperfusion. Representative Western blots of a single membrane are shown above the quantification from three experiments. P-p38 levels were quantified by densitometry and are expressed as the ratio of P-p38 to total p38 relative to the ratio of P-p38 to total p38 in sham-operated cPLA2α+/+ mice. B: Representative Western blots of MEK1/2 and ERK1/2 are shown. Relative levels of phosphorylated MEK1/2 (P-MEK1/2) and ERK1/2 (P-ERK1/2) were calculated as described in A. In all cases, actin was used as a control for loading. I, ipsilateral; C, contralateral; s/R and s/L, right and left side cortices of sham-operated mice (n = 3 from 3 mice). # P < 0.01; † P < 0.05.