VTCN1 and fibrosarcoma: Given that B7-H4 is highly expressed in almost all the examined cell lines from cancers of colon, prostate, lung, and stomach, and fibrosarcoma and melanomas [3–8] and in various human cancer tissues (Table 1), it could be hypothesized that the expression of B7-H4 represents a mechanism of downregulating antitumor immunity, particularly T-cell response, at the level of the effector cells [5].