There is also evidence that peripheral T cells of breast cancer patients are more susceptible to apoptosis, as indicated by the expressive proportion of Fas+ AnnexinV+ lymphocytes in circulation [84,97,98] (Figure 1, left); these cells are more often CD25− and occur in patients presenting a decrease in soluble Fas ligand (sFas-L) [97], suggesting that the pool of naïve and non-activated memory T cells is being selectively depleted by binding of sFas-L in circulation. The gene discussed is FASLG; the disease is breast cancer.