QKI and cataract: Mass spectrometric analysis demonstrated that the vast majority of the urea-denatured protein aggregates in Qk-deficient lenses belonged to the family of crystallins, including various isoforms of α-, β-, and γ-crystallins (Fig. 1g), which are the major components of human and mouse cataracts, suggesting that these aggregates are bona fide cataracts in Qk-deficient lenses.