More recently, yet another neuronal subtype was generated from fibroblasts. Remarkably, the overexpression of Ascl1, Brn3b and Ngn2 reportedly could convert MEFs and adult ear fibroblasts into induced retinal ganglion-like cells [37]. Since Ascl1 and Ngn2 are highly abundant general pro-neural transcription factors, the subtype specification is likely to be driven by the third factor of the pool Brn3b, a more restricted Pou-domain transcription factor. Although the induced retinal ganglion-like cells expressed the retinal ganglion cells markers RPF-1, Ath5 and Thy1.2, the cells remained electrophysiologically immature.
