BiP mRNA and protein are increased in rat models of rhodopsin RP.43, 44 Furthermore, BiP associates with rod opsin in the ER, and overexpression of BiP improved P23H rod opsin solubility.33 Indeed, overexpression of BiP via subretinal AAV delivery in P23H-3 rats increased BiP levels in the retina and preserved retinal function and ONL thickness.32 BiP levels were increased following arimoclomol treatment, suggesting that some of the protective effect might be mediated by increased BiP function. The gene discussed is HSPA5; the disease is retinitis pigmentosa 1.