To analyze the expressions of DNAM-1, TIGIT, and CD96 on tumor-resident immune cells, fibrosarcomas induced by 5 μg MCA in WT or CD155-deficient mice were resected and subjected to quantitative RT-PCR by using Cd2 expression, which is specifically expressed on T cells and NK cells, but not on non-hematopoietic cells, for normalization. The gene discussed is TIGIT; the disease is fibrosarcoma.