HSP90B1 and cystic fibrosis: Consistent with these observations, administration of CF via oral-gavage (20 mg/kg) also reduced circulating PCSK9 levels (Fig. S6) The protein and mRNA expression of UPR chaperones, GRP78, GRP94, IRE1α, and CHOP was also assessed via immunohistochemical staining, immunoblots and real-time PCR in the livers of these mice.