Protein expression levels of Bcl-2. (A) The apoptosis-associated protein Bcl-2 expression levels in HCT116 cells. Cells were treated with 31.25 nM DAC and either CPT-11 or SN-38. β-actin was used as a control. (B) Bcl-2 protein expression levels following normalization to β-actin. (C) Bcl-2 protein expression levels in HT29 cells treated with 75 nM DAC and either CPT-11 or SN-38. Cellular proteins were extracted 6 days after the start of culture. Data are expressed as mean ± standard deviation. *P<0.05 (one-way analysis of variance followed by Dunnett's test). Bcl-2, B-cell lymphoma-2; DAC, 5-aza-2′-deoxycytidine; CPT-11, irinotecan; SN-38, 7-ethyl-10-hydroxycamptothecin; Cont., vehicle control; C, 0.5 µM CPT-11; S, 1.0 nM SN-38; D, 31.25 (for HCT116 cells) or 75 nM (for HT29 cells) DAC.