BST2 and breast cancer: BST2 is upregulated in several malignancies,15 and high levels of BST2 are associated with poor prognosis in patients with oral cavity, esophageal, gastric and colorectal cancers.17, 36, 37 BST2 is also reported to promote the growth and metastasis of breast cancer.16, 38 Thus, BST2 may have a proto-oncogenic role and promotes cancer progression,38 which is also consistant with our observation that knockdown of BST2 delayed the growth of NPC xenografts in nude mice.