MKI67 and neoplasm: The tumor cells were highly proliferative, and the rate of Ki67‐positive cells was 34.6 ± 9.1% and 40 ± 12.3% for XtMCF and LmMCF xenografts, respectively, and 21.6 ± 4.7% for LmMCF lung metastases (Fig. 3I).