COL18A1 and hepatocellular carcinoma: To evaluate the functions of two previously defined anti-angiogenetic molecules, we first expressed and purified recombinant polypeptides HGFK1 (rHGFK1) and Endostatin (rEndo) (Figure 1A) and, then, studied their effects on the proliferation of endothelial cells and HCC cells via the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay.