We demonstrated that although both differentiation strategies yielded basically identical proportions of TH+ cells with neuronal morphology, the fraction of electrophysiologically mature TH+ DNs was significantly larger in the iPSC-derived culture than in the NPC-derived culture suggesting that the direct differentiation of iPSCs to DNs using the “midbrain floor plate protocol” (Kriks et al., 2011) has the higher conversion efficiency to mature TH+ DNs, which represent the most vulnerable cell type in PD. The gene discussed is TH; the disease is Parkinson disease.