ERBB2 and endometrial cancer: Both HER2-overexpressing endometrial cancer cell lines had significantly lower IC50 values compared with nonoverexpressing cell lines (Figure 1C; mean IC50 value 0.33 vs 4.15; P=0.024), and EGFR expression was significantly inversely correlated with IC50 values (Figure 1C; Spearman ρ, r=−0.57, P=0.011).