We also utilized the human breast cancer MDA-MB-231 cells expressing enhanced green fluorescence protein (EGFP) to investigate the effects of doxorubicin and/or the TGFβ antagonist TβRI-KI treatment on metastasis induced by orthotopic xenograft tumors formed by the MDA-MB-231 cells. This evidence concerns the gene TGFBR1 and breast cancer.