HGF and breast cancer: Kringle 1 domain of human hepatocyte growth factor (HGFK1) belongs to hepatocyte growth factor-α (HGF-α) chain and contains a high-affinity binding domain of MET [17, 18], which has been previously defined as a potent anti-angiogenic factor [19], and over-expression of HGFK1 also showed anti-tumor activities in breast cancer cells [20], colon cancer cells [21] and HCC [22, 23].