Relative truncation of αA E165 (A), αA E156 (B), βA3 Q208 (C), βA4 Q189 (D), βB1 E249 (E) and βB2 Q197 (F) in different regions of middle-aged normal human lenses. * indicates a statistically significant difference in truncation compared with WSF of the same regions of the lens (p < 0.05). $ indicates a statistically significant difference in truncation compared with cortex region of the lens. The error bars indicate standard deviation of four biological replicates (WSF = Water soluble fraction, USF = Urea soluble fraction and UIF=Urea insoluble fraction.)