Regional expression of Pax3 in the neonatal mouse brain. a qRT-PCR for Pax3 in RCAS-PDGF-B- versus RCAS-Y-infected brainstem progenitor cells. Pax3 levels are normalized to Actin. b-f Immunofluorescence for PAX3 (red) and DAPI (blue) (upper panels), and PAX3 (red) and Nestin-CFP (green) (lower panels) in P3 Nestin-CFPnuc brain; 20x magnification, scale bar is 50 μM in b dorsal pons (white arrows point to Nestin+/PAX3+ cells), c ventral pons, d 4th ventricle roof, e midbrain, f cerebral cortex. g The percentage of Nestin+ cells in each of the indicated brain regions that also express PAX3, quantified as described in the Methods section.