CREB1 and neuroblastoma: Metformin has been shown to decrease CREB phosphorylation and the CRE activity in epithelial cell line MCF-7 [142] but to increase CREB phosphorylation in neuroblastoma cell line SH-SY5Y [143, 144], suggesting again that Metformin effects on CREB phosphorylation is cell type-dependent.