MSTO parent, MSTO-CD26, JMN CD26-shRNA, JMN ctrl-shRNA, A549, Jurkat parent or Jurkat-CD26 cells were incubated with unlabeled isotype control or purified mouse anti-human CD26 mAb (19–32, U16-3 or U38-8) or purified goat anti-human CD26 pAb (R&D Systems), and subsequently stained with PE-labeled goat anti-mouse Ig pAb or PE-labeled donkey anti-goat IgG Ab, and analyzed by flow cytometry. PE-labeled commercial mouse anti-human CD26 mAb (BD Biosciences, clone M-A261) was utilized as a positive control. Representative data of three independent experiments are shown as mean ± S.D. of the mean fluorescence intensity (MFI) from triplicate samples, and similar results were obtained in each experiment.