NOTCH1 and medulloblastoma: To test if NOTCH1 activity was sufficient for Group 3 medulloblastoma metastasis, we restored the levels of NICD1 expression in Group 3 medulloblastoma cells, where NOTCH1 expression was reduced by shRNA (Supplementary Fig. 6a) by transfecting these cells with three constructs: (1) EF.hICN1.CMV.GFP, for constitutive expression of NICD1 and GFP, (2) doxycycline/RFP-inducible shRNA to NOTCH1, for NOTCH1 activity inhibition (Supplementary Fig. 6), and (3) luciferase, for constitutive expression of luciferase (shNotch1 + Dox + NICD1).