MSMB and Creutzfeldt Jacob disease: We previously found that CJD and PG14 PrPs are preferentially retained in the ER, while FFI PrP accumulates mainly in the Golgi [11,14,21,22], perhaps because organelle-specific factors such as ER chaperones or differences in pH influence the intrinsic misfolding tendency of these mutants in different ways [36–39].