Focused microarray analyses performed on RNA purified from splenocytes of vaccinated (protected) mice revealed that expression of interferon (INF)-γ was upregulated while programmed cell death protein 1 (PD-1) expression was down-regulated compared to splenocyte RNA from control mice, suggesting that semi-allogeneic vaccines are able to activate cytotoxic T cells and interfere with, or even block, the tumor-mediated induction of immune tolerance, a key mechanism underlying the suppression of anti-tumor immunity in the immune competent host [6]. This evidence concerns the gene PDCD1 and neoplasm.