GPR68 and medulloblastoma: GPR68 (OGR1) is one of at least four pHo-sensitive G-protein-coupled receptors (GPCRs) and is present in medulloblastoma tissue (Huang et al., 2008), rat HC neurons (Schneider et al., 2012), and rat anterior pituitary gland (Horiguchi et al., 2014).