dopamine neurons markers TH, DAT, AADC, and VMAT2 and were able to release dopamine. However, when tested in vivo, the cells only partially restored dopamine function and when a series of midbrain markers were analyzed both the 2-factor and the 6-factor iN cells failed to reach similar transcription levels found in embryonic or adult midbrain dopamine neurons. This finding leads to the somewhat sobering conclusion that even 6 transcription factors may still not be sufficient to fully reprogram fibroblasts to this specific neuronal subtype.
