Fig. 6. Characterization of lens fiber proteins in 3-month-old wt and SPARC-null lenses. Lens fiber cells from ^+/+ and SPARC-null (^-/-) animals were separated into cortical and nuclear fractions (see Materials and Methods). Proteins were extracted into water-soluble, urea-soluble and pellet (urea-insoluble) fractions and were resolved by SDS-PAGE under reducing conditions. Lanes 1, ^+/+ water-soluble cortex; 2, ^+/+ urea-soluble cortex; 3, ^+/+ pellet cortex; 4, ^-/- water-soluble cortex; 5, ^-/- urea-soluble cortex; 6, ^-/- pellet cortex; molecular weight markers (kDa); 7, ^+/+ water-soluble nucleus; 8, ^+/+ urea-soluble nucleus; 9, ^+/+ pellet nucleus; 10, ^-/- water-soluble nucleus; 11, ^-/- urea-soluble nucleus; 12, ^-/- pellet nucleus. The different fractions between ^+/+ and ^-/- lenses exhibit similar patterns, with no alteration of the major crystallins (arrow).