Fig. 4.

Localization of p55 and CASK at the apical surface of hair cells in WT, whirler (wi), and shaker2 (sh2) mutant mice during cochlear development. All images were taken from the apical turn of the cochlea. (A–L) Localization of p55 in WT and mutant mice during cochlea development. In WT mice, p55 labeling declines significantly around P14 (G and H) and fades out at P17 (data not shown). In the wi mutant, expression of p55 is normal until the P4 stage (P3 stage illustrated in C and D). However, labeling of p55 fades out from P5 in the wi mutant (I and J). Expression of p55 in stereocilia is completely ablated in the sh2 mutant (E, F, K, and L), although labeling of kinocilia (arrows) is still detected (E and F). (M–O) Localization of CASK in WT and mutant mice in mature hair cells. In WT mice, CASK signals were detected in stereocilia tips into adulthood in OHCs (N), but IHC labeling was not seen after P16 (M). CASK labeling is unaffected in both mutants in OHCs and IHCs (O and P and data not shown).