PTEN and neuroblastoma: In this study (201) with GRPR overexpressing in two human neuroblastoma cell lines (SH-N-SH and SH-SY5Y), there was decreased PTEN gene expression and increased expression of pAKT, suggesting that GRPR activation not only activated the PI3K signaling pathway but also downregulated the tumor suppressor gene PTEN, a negative regulator of PI3K (201).