Exogenous Ngn2 probably induces neural differentiation by activating a transcription factor cascade, including endogenous Ngn2. Consistent with its embryonic expression in the developing dorsal forebrain, Ngn2 produced one particular type of neuron that is characterized by specific markers, such as the presence of vGlut2, Cux1, and Brn2, suggesting that it may represent a relatively immature excitatory layer2/3 cortical neuron. It is possible that single use of another transcription factor, or addition of other transcription factors to Ngn2 in our protocol, will result in other types of neurons as shown previously for the BAM factor combination (Pfisterer et al., 2011; Caiuzzi et al., 2011; Son et al., 2011).
