AIM: To investigate the expression of genes involved in the gemcitabine-induced cytotoxicity in human pancreatic cancer cells.METHODS: A human pancreatic cancer cell line,PANC-1, was cultured. 1×104 PANC-1 cells were plated in 96-well microtiter plates. After being incubated for 24 h,gemcitabine was added to the medium at concentrations ranging 2.5 -1 000 mg/L. The AlamarBlue dye method was used for cell growth analysis. DNA fragmentation was quantitatively assayed using a DNA fragmentation enzyme-linked immunosorbent assay (ELISA) kit. PAP and TP53INP1 mRNA expression was determined using the reverse transcription-polymerase chain reaction with semi-quantitative analysis. The expression of GSK-3β and phospho-GSK-3β proteins was examined with Western blot analysis.RESULTS: The IC50 for the drug after a 48-h exposure to gemcitabine was 16 mg/L. The growth of PANC-1 cells was inhibited by gemcitabine in a concentrationdependent manner (P＜ 0.0001) and the cell growth was also inhibited throughout the time course (P＜0.0001).The DNA fragmentation rate in the gemcitabine-treated group at 48 h was 44.7 %, whereas it was 25.3 % in the untreated group. The PAP mRNA expression was decreased after being treated with gemcitabine, whereas the TP53INP1 mRNA was increased by the gemcitabine treatment. Western blot analysis showed that phosphoGSK-3βser9 was induced by the gemcitabine treatment.CONCLUSION: Gemcitabine suppresses PANC-1cell proliferation and induces apoptosis. Apoptosis is considered to be associated with the inhibition of PAP and GSK-3β, and the activation of TP53INP1 and posphoGSK-33ser9 .