In the liver, high levels of tissue inhibitor of metalloproteinases 1 (TIMP-1) secreted by hepatocytes upregulate stromal cell-derived factor 1 (SDF-1), fibronectin, TGF-β, urokinase-type plasminogen activator (uPA), and S100A, inducing homing of breast cancer cells to this distant microenvironment (Seubert et al., 2015) (Figure 2D). This evidence concerns the gene PLAU and breast carcinoma.