VWF and neoplasm: However, such an apoptosis function of VWF is not universal and can be depressed by a VWF cleavage protease, ADAM28 (a disintegrin and metalloprotease domain 28), secreted by many other types of tumor cells, suggesting that the role of VWF in cancer metastasis is not simple and may vary in different types of tumor cells (Mochizuki et al., 2012).