The staining of this tissue was confirmed at 28 to 31 days after tumor cell inoculation, and since PD-L1 expression in PD-1 antibody therapy to tumor-bearing mouse in vivo was around 9 days after tumor cell inoculation, the expression of MHC class-I also peaked around day 10, similar to PD-L1 expression, and then MHC class-I expression may have peaked around day 10, as was the case with PD-L1 expression, and then decreased due to down-regulation. The gene discussed is PDCD1; the disease is neoplasm.