XBP1 and necrotizing enterocolitis: In tissue of a subset of patients with acute NEC splicing of the ER stress related protein X-box binding protein 1 (XBP1) was detected with concomitant increased mRNA and protein expression of ER stress markers binding immunoglobulin protein (BiP) and C/EBP homologous protein (CHOP), suggesting increased ER stress [190].