SMO and medulloblastoma: Compensatory up-regulation of IGF-1R-PI3K is a candidate for the development of Smo antagonist resistant medulloblastoma, and combination of PI3K inhibitor NVP-BKM120 or the dual PI3K-mTOR inhibitor NVP-BEZ235 with the Smo antagonist markedly delayed the development of resistance [60].