Blocking experiment of novel anti-CD26 mAb binding to CD26. Jurkat-CD26WT cells were pretreated with unlabeled mouse anti-CD26 mAbs (4G8, 1F7, 5F8, 16D4B, or 9C11) (blue lines) or mouse IgG1 isotype control (Contl. IgG) (red lines), and subsequently stained with PE-labeled anti-mouse Ig pAb (i) or Alexa Fluor 647-labeled anti-CD26 mAbs (clone 18 (ii) or clone 19 (iii)), and analyzed by flow cytometry. The representative histograms of CD26 expression are shown, and the gray areas in each histogram show the data involving the isotype control. Data shown are repeated twice with similar results.