Figure 2.

ERBB3 activity is increased in the absence of EGFR in Lrig1 null duodenal tumors. (A) Representative blots from 3 independent mouse RTK arrays (R&D Systems, Minneapolis, MN). (B) Relative activity of ERBB2, ERBB3, RON, and PDGFRA in TAM-treated group compared with CTL, calculated from RTK array. Red bars indicate 95% confidence intervals. (C) Greyscale immunofluorescence for ERBB3 in TAM-treated and CTL mice. Arrows and arrowheads indicate tumor cells and stroma, respectively. (D) Comparison of Nrg1 expression by microarray analysis between duodenal tumors and adjacent normal duodenum in Lrig1 null mice. (E) Immunofluorescence for NRG1 (green) with DAPI (purple) in duodenal tumors from CTL and TAM-treated mice. Scale bar = 100 μm.