Notably, in cancers such as COAD, BRCA, LUAD, READ, and CESC, tumors in the low-succinylation group exhibited elevated expression levels of PDCD1 (PD-1), CD274 (PD-L1), and CTLA4 at both the transcriptional and protein levels (Figures 4C–E). Here, PDCD1 is linked to cervical squamous cell carcinoma.