Western blot analysis

HCT116 cells were homogenized in the lysate buffer, and the total proteins were prepared. Using a commercial mitochondria/cytosol fractionation kit (Beyotime, Shanghai, China), the cytosolic and mitochondrial proteins were obtained separately. The cell cycle arrest-related proteins of p53, p21, Cyclin E1, and CDK2; the ER stress-associated proteins of p-IRE1α, IRE1α, p-PERK, PERK, ATF6, XBP-1s, p-eIF2α, eIF2, ATF4, and CHOP; and the apoptosis-associated proteins of Bax, Bcl-2, cytoplasmic cytochrome c (Cyto Cyt C), mitochondrial cytochrome c (Mito Cyt C), caspase-9 and -3 as well as cleaved caspase-3, were all evaluated by western blot analysis.