Since previous studies in cellular and animal models of HD have reported defects in BDNF-mediated activation of TrkB-Erk1/2 rather than the-Akt pathway (Ginés et al., 2010; Brito et al., 2013), we assessed the levels of activated phospho-Erk1/2 to characterize transduction downstream of TrkB in R6/2 cultures. The gene discussed is MAPK3; the disease is Huntington disease.