FIG. 4.

Duct cell replication frequency is increased in the pancreas of exendin-4–treated Pdx1-Kras mice. Immunohistochemical labeling of Ki-67–positive cells (brown; counterstained with hematoxylin) in benign ducts in areas of intact acinar tissue in control mice (A) and exendin-4–treated mice (B). An area of ductal proliferation embedded in fibrotic tissue shows an increase in Ki-67–positive cells in the exendin-4–treated group (D) compared with controls (C). Note the presence of proliferative ducts and mPanIN1a lesion in the exendin-4–treated animal. E: Analysis of duct cell proliferation by Ki-67 reveals an increase in the replication frequency in Pdx1-Kras mice treated with exendin-4 (Ex; ■) compared with vehicle control (Ctrl; □). *P < 0.05. (A high-quality digital representation of this figure is available in the online issue.)