  HCT-116 (A, B) or HT-29 (C,D) cells were treated with 0.1μM mithramycin for 30 min followed by sodium butyrate (NaB) for 24 h. Representative Western blots showing the expression of IRE-1a, BIP, and PDI in HCT-116 (A) or HT-29 (C) cells are shown. GAPDH was used as loading control. Protein expression (IRE-1a, BIP, and PDI) was quantified by densitometry and normalized to GAPDH (ratio of protein:GAPDH). The fold change from control for each protein is expressed as mean ± SD of three independent experiments for HCT-116 (B) and HT-29 (D) cells. One-way ANOVA was used for statistical analysis. * P<0.05, ** p<0.01, compared to the respective control group. 