On the other hand, TGC-specific AIs have also received considerable attention because of their role as cancer/testis antigens (CTs)3334. CTs are protein antigens with expression normally restricted to adult TGCs and yet they become aberrantly activated in and expressed by a proportion of various types of cancer, including melanoma, lung cancer, and pancreatic cancer333435. Hence, CTs are promising candidates for cancer immunotherapy targets and have become a major focus of vaccine-based clinical trials in recent years. Thus, information on the testis-specific proteins and proteins expressed after puberty may reveal additional biomarker candidates for cancer diagnosis/prognosis.