AR and spinocerebellar ataxia 7: Using these mice, it has been demonstrated that UPS function is preserved in animals expressing polyQ-expanded proteins such as the N-terminal huntingtin fragment, R6/2 (Bett et al., 2009; Maynard et al., 2009; Ortega et al., 2010), androgen receptor (AR) responsible for SBMA (Tokui et al., 2009), and ataxin-7 that causes SCA-7 (Bowman et al., 2005).