DRD1 and Huntington disease: For the case of D1R-H3R heteromers, it appears that they are stable enough that they can affect both rapid receptor signaling (e.g., Ca2+ mobilization) and longer cell signaling pathways like p38, two events that have previously been involved in neuronal cell death in HD (Dau et al., 2014; Fan et al., 2012; Muller and Leavitt, 2014; Taylor et al., 2013; Wang et al., 2013).