Since IFN-γ exerts an important role in regulating PD-1-dependent inflammatory responses, at least in tumor immunology, and since PD-1-/- caused significantly greater increase of muscle IFN-γ mRNA after hindlimb ischemia, we further determined muscle IFN-γ protein content in muscles with or without ischemia from both PD-1-/- and WT mice, and the result demonstrated that PD-1-/- mice significantly increased (1.55 fold) muscle IFN-γ protein in muscle after ischemia (Figure 2Q). This evidence concerns the gene PDCD1 and neoplasm.