However, there were no significant difference in Ki67 staining between RM11A+Dox tumor cells (Figure 4c) and RM11A+Dox/ErbB2 tumor cells 14 d post injection (Figure 4d), suggesting that ErbB2 increases tumor growth rate during the first few days of tumor development but not once tumors have been established. The gene discussed is MKI67; the disease is neoplasm.