HRH3 and neuroblastoma: Similar to other G protein-coupled receptor (GPCR) signaling transduction, H3R activation results in AKT phosphorylation at Ser 473 and subsequently GSK3β hyperphosphorylation occurring from increased phosphorylation of S9 through PI3K activation via the Gβγ-subunits of Gαi/o proteins, previously demonstrated in a neuroblastoma cell line, primary cultures of cortical neurons, and in striatal slices of Sprague-Dawley rats (Bongers et al., 2007).