N-Myc and L-Myc are essential for hair cell formation but not maintenance

► Proto-oncogenes N-Myc and L-Myc are strongly expressed in organ of Corti hair cells. ► Late deletion of the Mycs after hair cell differentiation shows no loss of hair cells. ► Cisplatin application does not disproportionately affect mutant hair cells. ► Loss of hair cells in Pax2-Cre N-Myc mice is likely due to defect in proliferation. ► N-Myc and L-Myc are unlikely to play a role in therapeutic prevention of hearing loss.