[[Auditory hair cell]]s are the mechanical [[sensor]]s of sound waves in the [[inner ear]], and the [[stereocilia]], which are [[actin]]-rich protrusions of different heights on the apical surfaces of hair cells, are responsible for the [[transduction]] of [[sound]] [[wave]]s into electrical signals. As a crucial [[actin]]-binding and bundling protein, [[espin]] is able to cross-link actin filaments and is therefore necessary for [[stereocilia]] morphogenesis. Using advanced super-resolution stimulated emission depletion microscopy, we imaged espin expression at the sub-diffraction limit along the whole length of the stereocilia in outer hair cells and inner hair cells in order to better understand espin's function in the development of stereocilia ((Qi J, Zhang L, Tan F, Liu Y, Chu C, Zhu W, Wang Y, Qi Z, Chai R. Espin distribution as revealed by super-resolution microscopy of stereocilia. Am J Transl Res. 2020 Jan 15;12(1):130-141. PMID: 32051742; PMCID: PMC7013225.)).