EGFR and adenoma: To investigate the possibility that Egfr activation was involved in the pathobiology of these PNET tumors, we treated cohorts of RT2 mice with different EGFR inhibitors (gefitinib, CI-1033, erlotinib) for 3 to 4 weeks beginning at 11 to 12 weeks of age, a stage at which small adenoma are already present.