RUNX3 knockdown in pancreatic cancer cell lines. RUNX3 siRNA and control siRNA were transfected into the endogenous RUNX3‐positive cell lines SUIT‐2 and KLM‐1. (A) Immunoblot analysis of RUNX3 and MRP expression. Immunoblot analysis was performed using antibodies against RUNX3, MRP1, MRP2, MRP5, and α‐actin. Immunoblotting for α‐actin was done to verify equal loading. These 2 cell lines were originally endogenous RUNX3 positive. The left lane for each cell line represents mock‐transfected cancer cells, and the right lane represents RUNX3 siRNA‐transfected cancer cells. Representative blots of more than 3 independent experiments. (B) Cell growth activity. Cell proliferative activities were measured by MTT assay. Results are expressed as ratios compared to day 1. Data represent the means ± SE of more than 3 independent experiments performed in triplicate. **P < 0.01, versus control siRNA‐transfected cells (Student's t test). (C and D) Gemcitabine sensitivity. SUIT‐2 (C) and KLM‐1 (D) cell lines were treated with various concentrations of gemcitabine for 24 h. Cell viability was measured by MTT assay and expressed as a percentage relative to control cells. Data represent the means ± SE of more than 3 independent experiments performed in triplicate.