In our preliminary experiments of making metastatic murine breast cancer models by using either 4T1 or 4T1‐EGFP tumor cells separately (more than ten pairs of EphA4‐KO and control WT mice for each cell line), both 4T1 and 4T1‐EGFP tumor cells can be used to make metastatic murine breast cancer models successfully. This evidence concerns the gene EPHA4 and neoplasm.