D. Lysates of N2a cells transfected with either WT or S309D were immunoblotted to detect Atoh1 S328 phosphorylation (p-S328-Ab), Atoh1 or β-actin. Quantification of relative levels of phosphorylated ATOH1 at S328 to the total ATOH1 (right panel). Mean± s.e.m. Student T-test between WT and S309D was performed. **p < 0.01. Three slots of each experimental condition represent the three biological replicants of each condition. 