As expected, the majority (70–80%) of medulloblastoma CPCs were positive for the neural stem cell marker Sox2 and TGFβ inhibitor treatments had no effect on the proportion of Sox2 expressing cells (Fig. S2a), indicating that Sox2+ cell identity or Sox2 expression were not dependent on TGFβ signalling. Here, TGFB1 is linked to medulloblastoma.