PDCD1 and melanoma: When comparing the expression profiles of the TCGA CRC subgroups and this external melanoma cohort, we observed that group III had a significant correlation with the PD-1 response group (Bonferroni corrected p = 0.012; Fig. 5e), a finding that was validated in the GSE39582 dataset (Bonferroni corrected p = 0.012; Fig. 5f).