The neurogenin family, neurogenin 1 through 3, make up a subset of the basic-loop-helix transcription factors. Neurogenin-1 is expressed only in embryonic neural tissue and supports neuronal differentiation, but appears to inhibit glial differentiation. Neurogenin-2 is required for neurogenesis and may be used as a marker of neuronal differentiation. Neurogenin-3 expression is required for endocrine lineage differentiation in the pancreas, including formation of islet beta cells. Neurogenin-3 is also neurogenic, regulating dendrite growth and the formation of synaptic connections.