Considering leukocyte antigen-class I (HLA-I) surface level is known to represent the antigen-presenting abilities of tumor cells (Brea et al., 2016; Jhunjhunwala et al., 2021; Oh et al., 2019), we assessed HLA-I expression in PCC cells: the expression levels of HLA-A, HLA-B, and HLA-C were significantly lower in kinase-type PCC cells than in metabolism-type PCC cells (Figure 7B). Here, HLA-A is linked to neoplasm.