PTCH1 and Mobius syndrome: Our results suggest that Sox2+ SHH-MB cells resist radiation-enhanced p53R172P-dependent cell-cycle arrest and neuronal differentiation, which is mediated by p21 expression.24 To investigate the underlying mechanism, we analyzed published microarray data sets of Sox2+ and Sox2− cells isolated from SHH-MBs in a similar p53-WT Ptch1+/− model.21 Between these two populations, 107 genes were significantly upregulated in Sox2+ SHH-MB cells (Supplementary Figure S5A), whereas Sox2− SHH-MB cells had 7 upregulated genes (P < .01) (Supplementary Figure S5B).