Figure 3. SDS–PAGE analysis of the soluble proteins in concentric layers from a 20-month-old eastern gray kangaroo. Sample numbers indicate the order in which the layers were removed from the lens, with layer 1 corresponding to the outer cortex + epithelium and layer 12 the most central region. The average age of each layer, in months, is indicated. Standard protein sizes (kDa) are indicated on the left.