SPAG9 and esophageal squamous cell carcinoma: By using the proteomic data, four known CT antigens, MAGE family member B2 (MAGEB2), MAGE family member A4 (MAGEA4), MAGE family member A8 (MAGEA8), and sperm‐associated antigen 9 (SPAG9), were found to be significantly increased in ESCC tumors with FC range from 1.84 to 223.50 as compared with NATs (adjusted p < .05, FDR q < .05) (Figure 10A).