A. Exogenous expression of Math1 in bone marrow MSCs resulted in green cells and nuclei due to the expression of GFP from the vector. B. Expression of Math1 followed by treatment of the cells with NT3, FGF and BDNF, gave rise to progenitor cells that subsequently matured into cells expressing hair cell genes, including espin, myosin VIIa, jagged 2, and Brn3c, and p27Kip, in addition to the proneural genes, Ngn1 and NeuroD. C. The cells under these differentiating conditions also expressed S100A, p75Trk, claudin 14, connexin 26, and Notch1, consistent with some cells having a supporting cell phenotype. D. MSC cell line selected in Zeocin had a high percentage of GFP expression when cultured in serum. E. After differentiation, the number of hair cell-like cells per DAPI nucleus rose and these cells stained for myosin VIIa (shown in red) and Math1 (shown in green; arrows). F. Math1 expressing cell line differentiated to cells with nuclei that were immunopositive for Brn3c (green; arrowheads) and cytoplasm positive for myosin VIIa (red; arrows). Nuclei were stained with DAPI (blue). G. The differentiated cells were positive for both espin and F-actin in protrusions at the apex of the cell (arrow). Scale bars are 25 μm.