BST2 and neoplasm: The decrease in lung metastasis in shBST-2 and OE-BST-2M tumor-bearing mice could be attributed to smaller primary tumors, although the effect of BST-2 on primary tumor is distinct from its effect on lung metastasis.3 Alternatively, dimerization-competent OE-BST-2D cancer cells could associate with BST-2-expressing lung-associated cells, and such association may protect cancer cells from apoptosis.