We also used additional assay formats to determine TrkB receptor activation status, which included: a) direct measurement of signal transduction phosphorylation events by western blot (phospho/total AKT, phospho/total ERK1/2 and phospho/total TrkB), b) Meso Scale Discovery assay for quantitative measurement of phospho/total AKT in the human neuroblastoma cell line, SH-SY5Y, which expresses endogenous TrkB upon retinoic acid differentiation, and c) an HD relevant primary neuronal mHTT-induced cell death assay, where BDNF is neuroprotective for striatal neurons. The gene discussed is MAPK3; the disease is neuroblastoma.