Interestingly, as we found the correlation features of TIM3, LAG3, PD-1, and TIGIT with PRRs are similar in melanoma, we checked their correlation within each other, and found their expressions are also highly correlated with each other in melanoma (R>0.82) (Figure 4C), suggesting there are some molecular subsets of clinical relevance in SKCM which could be considered combinedly in medical research and clinical treatment. The gene discussed is PDCD1; the disease is melanoma.