XBP1 and malignant colon neoplasm: For example, the up-regulation of inositol-requiring enzyme 1α (IRE1α) and X-box binding protein 1 (XBP1) pathway is shown to cause drug resistance to 5-flurouracil through the expression of efflux transporters, ABCB1, ABCC1, and ABCG2 in colon cancer cells [13].