We found increased expression of GRP94, the 94-kDa glucose-regulated protein, in HeLa cells 24 h after treatment with luteolin. Luteolin increased the levels of GRP94 mRNA and protein, but it did not increase the expression of unfolded protein response (UPR)-regulated genes. In addition, luteolin also enhanced GRP94 promoter activity, suggesting that it enhances the expression of GRP94 at the transcriptional level, not via the UPR signaling pathway.
