GLI1 and medulloblastoma: Interestingly, in a subset of Ptc1+/− mice with the loss of GLI1 that still develop medulloblastoma, GLI2 expression was significantly upregulated and correlated with the levels of n-Myc, a regulator of D-type cyclins in neuronal cells, suggesting a compensatory GLI2/n-Myc expression in promoting medulloblastoma formation and proliferation [53].