ANPEP and sarcoma: Since tumor cells, such as HT1080 sarcoma cells, express CD13 and can also form part of the inner cellular lining of tumor neo-vasculature, this being described as vascular mimicry [28], we have also tested the pro-coagulant behaviour of HT1080 sarcoma cells following irradiation as a further mechanism explaining the combinatorial effect, and have obtained similar results as with stimulated HUVEC.