Figure 4

ERBB family members and downstream effectors of ERBB signaling are not affected by Erbb2 loss. (A) Immunofluorescent labeling for EGFR, P-EGFR, ERBB3, and Amylase in WT and ElaC^ER Erbb2^KO mice treated for 1 week with cerulein (W1) and in ElaC^ER Kras^G12D and ElaC^ER Erbb2^KO Kras^G12D mice treated for 3 weeks with cerulein (W3). EGFR and ERBB3 are both expressed, and EGFR is activated in ADM in WT and ElaC^ER Erbb2^KO pancreas (white arrows) and in PanIN present in ElaC^ER Kras^G12D and ElaC^ER Erbb2^KO Kras^G12D pancreas. DAPI staining visualizes cell nuclei. Scale bars = 50 μm. (B) Immunohistochemical staining for P-ERK^T202/204 and P-AKT^T308 after 3 weeks of cerulein treatment (W3). Similar proportions of ADM are positive for P-ERK and P-AKT in WT and ElaC^ER Erbb2^KO mice whereas a large number of PanIN are stained by both antibodies in ElaC^ER Kras^G12D and ElaC^ER Kras^G12D Erbb2^KO mice. High activity of the AKT pathway is detected in the pancreata of the different genotypes. Scale bars = 50 μm.