To test whether D1R-H3R heteromers could indeed be targets for controlling D1R signaling in HD, we first analyzed the expression of both receptors in immortalized striatal cells expressing endogenous levels of full-length wild-type STHdhQ7 or mutant STHdhQ111 huntingtin (Ginés et al., 2010). The gene discussed is DRD1; the disease is Huntington disease.