In MCF-7 human breast cancer cell lines, 3-6-methoxylated flavonoids: Jacein and 3-demethyljacein from C. schmidii induced ER stress related apoptotic cell death by increasing protein aggregation as demonstrated by fluorescence microscopy analysis and by the marked increase in gene expression of XBP1, sXBP1, ATF-4, and ChoP proteins. Here, XBP1 is linked to breast cancer.