Post‐TZM treatment, the H&E staining shows a decrease in cellularity in AU565 and XTM tumors compared to that in SKOV‐3, suggesting that TZM induces elevated cytotoxicity in HER2‐positive breast tumor xenografts in comparison to ovarian tumor xenografts (Figure 3A, H&E). The gene discussed is ERBB2; the disease is breast neoplasm.