PTGER4 and neoplasm: However, in addition to the widely accepted stemness-related markers CST7, CCR7 and TCF7, other cluster-specific markers of CD8.c05, such as SIPR1 and ENC1 (Figure 1I, Supplementary Figure S2A), as well as MPR-enriched DEGs such as PTGER4 and SRSF2 (Figure 1G), still lacked certain research related to their roles in tumor immunology, which made the features of CD8.c05 even more unclear.