The presumptive sensory patches of the inner ear
express a defining combination of markers that include the
signaling proteins BMP4 and BMP7, the Notch-ligand
Jagged-1 and the cell-cycle modulator p27 Kip1 (Figure 1d–f)
[37–42]. Concurrently, early sensory patches lack the
expression of markers for differentiated or differentiating
cell types, such as the hair-cell markers Math1, Brn3.1,
myosin VIIA and espin. This temporal expression pattern
of markers is also reflected in stem-cell-derived inner-ear
progenitor cells [3,4]. Hair-cell differentiation from inner ear-
derived stem cells was apparent by the substantial