GNAS and medulloblastoma: DDX3X and GSE1 are potent medulloblastoma tumor suppressors in Gorlin 1 NES cells, PRKAR1A with its upstream g-protein GNAS are both regulators of Shh activity through cAMP, and CREBBP has been shown to promote cell-cycle exit during postnatal development in coordination with Shh pathway upregulation.