Zhangfei negatively regulates the Unfolded Protein Responses (UPR) in canine osteosarcomas. (A) D–17 cells were left untreated, treated with thapsigargin or grown in glucose free medium. Twelve hours later cells were harvested and transcripts for the UPR- linked genes Xbp1s, HERP, CHOP and GRP78 estimated by qRT-PCR. Cells were mock-infected or infected with either Adeno-ZF or Adeno-LacZ and then treated with thapsigargin (B) or deprived of glucose (C). 24 hr later cells were harvested and transcripts for UPR genes estimated. Proteins in thapsigargin-treated mock-infected and Adeno-ZF-infected cells were detected by immunoblots (D) and immunofluorescence (E). Dotted lines in A and B indicate a 2-fold difference. Values greater than 2 fold were considered significant.