Fig. 4: The absence of TUBB4B leads to reduction in microtubules.

A Immunoblot analysis of cochlear lysates from 1-month-old wildtype and Tubb4b^−/− littermates, probed with β-tubulin antibody. The blots were also probed for GAPDH, a housekeeping protein, serving as a loading control. The molecular weights in kDa are indicated on the left. B Quantification of β-tubulin levels from (A), normalized to total protein. Data are presented as mean ± SEM (n = 6, unpaired t test, two-tailed). C Cochlear whole mounts from 1-month-old mice wildtype and Tubb4b^−/− littermates, stained with acetylated tubulin (magenta), α-tubulin (green) antibodies, and phalloidin (blue). The double arrow denotes the inner pillar cell head. Scale bar = 10 μm. D Inner pillar cell head length measured using acetylated tubulin staining of cochlear whole mounts from the apical turns of 1-month-old wildtype and Tubb4b^−/− littermates. Data are presented as mean ± SEM (n = 3, Mann–Whitney U test). *** denotes a significance level of P < 0.001. E Cochlear wholemount images from basal turns of 1-month-old wildtype and Tubb4b^−/− littermates, stained with α-tubulin (green). Scale bar = 10 μm. F Deiters’ cells phalangeal processes, cup, and stalk diameters measured from basal turns of 1-month-old wildtype and Tubb4b^−/− littermates, stained with α-tubulin. Data are presented as mean ± SEM (n = 3, unpaired t test, two-tailed). *** denotes a significance level of P < 0.001; ns not significant. G Schematic illustration of Deiters’ cells phalangeal processes, cup and stalk locations used for diameter measurement. OHC outer hair cell, DC Deiters’ cell.