Figure 2. SDS–PAGE and western immunoblot analysis of human lens membranes. Isolated cortical and nuclear lens membranes were extracted with 7 M urea in Tris buffer (CU – cortex urea; NU – nucleus urea) and with 0.1 M NaOH (CA – cortex alkali; NA – nucleus alkali). Samples were analyzed by SDS–PAGE (100 μg of membrane per lane) and with western immunoblotting (20 μg of membrane per lane). Blots were probed using anti-αA-crystallin, anti-αB-crystallin, anti-filensin and anti-vimentin antibodies, as indicated. Molecular weight markers are on the left of the figure.