Furthermore, independent studies have shown that the mutant polyglutamine-expanded androgen receptor, responsible for SBMA, activates the unfolded protein response, an endoplasmic reticulum protein quality control pathway (Szegezdi et al., 2006), both in vitro (Thomas et al., 2005) and in vivo, in a mouse model of SBMA (Yu et al., 2011). Here, AR is linked to Kennedy disease.