XBP1 activation involves an unconventional splicing event mediated by the ER stress sensor IRE1α. When cells experience ER stress, IRE1α splices XBP1 mRNA, producing a spliced variant known as XBP1s. This spliced form is a potent transcription factor that upregulates genes involved in protein folding, secretion, and degradation, thereby alleviating ER stress.
