Effects of ouabain on phosphorylation of the mitogen-activated protein kinases in HUVEC and RAEC. A, Representative Western blots showing the effects of ouabain on the content of phosphorylated ERK1/2, JNK1/2 and p38 MAPK. HUVEC and RAEC were treated during 6 hr with 3 and 3,000 μM ouabain, respectively. B, Normalized changes in the immunoreactivity of phosphorylated ERK1/2, JNK1/2 and MAPK in ouabain-treated HUVEC and RAEC. The immunoreactivity of phosphorylated MAPKs in control cells, which were not treated with ouabain, was taken as 1.00. Means ± S.E. from 3 experiments are shown.