Fig. 5B shows the constant tumor volume ratio of erlotinib group to vehicle group after around Day 8. On Day 20, the mice in the erlotinib group were randomly allocated to 4 groups, namely, vehicle group, erlotinib group, gemcitabine group, and gemcitabine + erlotinib group. Although EGFR protein remained positive and its phosphorylation had been substantially reduced by erlotinib by Day 21 (Fig. 5C), the erlotinib group did not show significant tumor growth inhibition compared with the vehicle group (Fig. 5D). This evidence concerns the gene EGFR and neoplasm.