DPP4 and lung cancer: Namely, ACE2 has validated significant differential expression in colon, kidney, testicular and thyroid cancers; TMPRSS2 has validated significant differential expression in breast, colon, head and neck, kidney, lung, skin and uterus cancers; CLEC4M has validated significant differential expression in liver, lung and ovary cancers; DPP4 has validated significant differential expression in breast, kidney, blood, skin, stomach and thyroid cancers; and TNPRSS11D has validated significant different expression in lung cancer.