The present invention relates to the use of a regulatory nucleic acid sequences that are able to regulate gene expression in eukaryotic cells and which are responsive to the unfolded protein response (UPR). There are disclosed regulatable introns and UPR-inducible promoters, which are able to regulate gene expression. There are also disclosed recombinant expression constructs comprising such regulatory nucleic acid sequences, whereby expression of the encoded expression product can be induced by invoking the unfolded protein response (UPR) in a eukaryotic cell containing the construct, methods of using such constructs and associated vectors, cells and suchlike.
