The HPV-16 E5 protein represses expression of stress pathway genes XBP-1 and COX-2 in genital keratinocytes

► HPV16 E5 downregulates an important stress signaling pathway: decreases spliced XBP-1 mRNA and IREα in human genital keratinocytes. ► HPV16 E5 decreases expression of COX-2 (downstream of XBP-1). ► Co-expression of the HPV-16 E6E7 genes partially alters the E5 phenotype. HPV-16 E5 cannot inhibit chemically-induced ER stress.