XBP1 and cancer: In addition, when ERAIm454–557 is expressed in several cell lines including cancer cell lines, such as MCF-7, MDA-MB-231, HeLa, Du145, PC3 and HCT116, and normal cell lines, such as NIH3T3, HLB-100 and MCF-10A, obvious fluorescence is observed in the normal cell culture condition (data not shown), and therefore, the basal machinery underlying acute ER stress-independent splicing of XBP1 mRNA possibly represents an ubiquitous phenomenon.