Effects of AST on UPR activation (A) and ER stress-induced apoptosis (B) on HCT116 colon cancer cells. HCT116 colon cancer cells were treated with AST (80 μg/ml) for different time intervals (4–96 h). Specific antibodies against GRP78, GRP94, XBP-1s and CHOP were used in Western immunoblotting to detect the expression of different proteins. Data shown are representative immunoblots with similar findings, normalized by β-actin. Blots were scanned and optical densities were determined using the Quantity One software. Each histogram represents mean ± SEM of four independent experiments. *p <0.05 compared with the protein level at zero time.