Figure 4. Phosphorylated extracellular signal-regulated kinase 1 and 2 (ERK1/2) immunofluorescence in the retina. Immunofluorescence staining of retina from pigs subjected to ischemia followed by 5 (n=4), 12 (n=5), or 20 (n=4) h of reperfusion and the corresponding sham-operated eyes. Note the enhanced staining for phosphorylated ERK1/2 following retinal ischemia, especially after 5 h of reperfusion. Immunofluorescence staining for ERK1/2 appears to be located in the Müller cells, including both the cell bodies and in the radial processes, and in the inner retina, probably corresponding to Müller cell endfeet and astrocytes. The abbreviations used in the figure are outer nuclear layer (ONL), inner nuclear layer (INL), and ganglion cell layer (GCL).