Further, with ShMCT4 vectors, the 4T1 cells expressing MCT4 were obtained by transfection, and in accordance with the inference efficiency, were divided into groups “1,” “2,” and “3.” When the transfected 4T1 cells were injected subcutaneously (s.c.)into the mice, we noticed that as the silence efficiency declined, the tumors diminished in size in the ShMCT4 groups; the concentration of the CD107a and the perforin decreased and the weight of the tumor increased at the same time (*P < 0.05 vs. the control group of with null vector transfection, Figures 2B and 3A). This evidence concerns the gene PRF1 and neoplasm.