CD274 and cancer: There were 10 KEGG pathways present in all ascidian species: biosynthesis of antibiotics, purine metabolism, glycolysis/gluconeogenesis, thiamine metabolism, methane metabolism, pentose phosphate pathway, glyoxylate and dicarboxylate metabolism, Programmed cell death 1 (PD1) and its ligand(PD-L1) checkpoint pathways in cancer, T cell receptor signaling pathway, and T helper type 1 (Th1) and type 2 (Th2) cell differentiation (Table 2).