Additionally, DA2 neurons in both species express ALDH1A, an enzyme involved in the synthesis of retinoic acid (McCaffery and Drager, 1994), and LMO3, a TF highly enriched in the murine SNc, which functions as a transcriptional co-regulator of PITX3 (Bifsha et al., 2017) and has also been suggested to play a role in Parkinson’s disease (Briggs et al., 2015). Here, LMO3 is linked to Parkinson disease.