BSG and neoplasm: Furthermore, the surface of DTCs is characterized by reduced expression of MHC class I molecules, which could result in an immune escape of these cells [33], as well as high activity of tumor invasiveness markers, such as urokinase plasminogen activator (uPA) and its membrane receptor (uPA-R), extracellular matrix metalloproteinase inducer (EMMPRIN) or cathepsin B, which enables destruction of basement membrane and stromal invasion [34,35,36,37].