In addition to their cytotoxic activity, CD8+ and CD4+ T cells have been previously shown to limit tumor growth through the secretion of anti-proliferative cytokines, such as interferon γ which can stimulate the expression of p21 and p27 cell cycle inhibitors (Chin et al., 1996; Wall et al., 2003), and antiangiogenic chemokines, such as CXCL9 and CXCL10 (Ikeda et al., 2002). Here, CD4 is linked to neoplasm.