Immunocytochemistry and staining procedures were as described previously [12]. Briefly, hESCs at different stages of dopaminergic differentiation were fixed with 2% paraformaldehyde for half an hour. Fixed cells were blocked in blocking buffer (10% goat serum, 1% BSA, 0.1% Triton X-100) for 1 hour followed by incubation with the primary antibody at 4°C overnight in 8% goat serum, 1% BSA, 0.1% Triton X-100. Appropriately coupled secondary antibodies (Molecular Probes, Carlsbad, CA http://www.invitrogen.com/site/us/en/home/brands/Molecular-Probes.html) were used for single and double labeling. All secondary antibodies were tested for cross reactivity and nonspecific immunoreactivity. The following primary antibodies were used: Oct4 (ab19857 AbCam, Cambridge, MA http://www.abcam.com) 1:1,000; β-Tubulin isotype III clone SDL.3D10 (T8660 Sigma, St. Louis, MO http://www.sigmaaldrich.com/united-states.html) 1:500; GalC (MAB342 Millipore, Billerica, MA http://www.millipore.com) 1:50; Glial fibrillary acidic protein (GFAP) (M0761 Chemicon) 1:50; Nestin (611658 BD Transduction laboratories) 1:500; Sox1 (AB5768 Chemicon Billerica, MA http://www.millipore.com) 1:800, TH (Pel-freez, Rogers, AR http://www.pelfreez-bio.com P40101) 1:500, TH clone TH-16 (T2928 Sigma) 1:1,000; Girk2 (Alamone) 1:250; Musashi (eBioscience, San Diego, CA http://www.ebioscience.com) 1:50, and as secondary antibodies: Alexa Fluor 488 Goat Anti-Mouse, Alexa Fluor 594 Goat Anti-Mouse,
