PGC and lung cancer: For example, TTF-1 and surfactant proteins (SP-A, pro-SP-B, pro-SP-C) can be used to identify lung cancer, thyroglobulin to thyroid, prostate specific antigen to prostate, mammaglobin 1 to breast, pepsinogen C to stomach, metallothionein IL to pancreas, uroplakin II to bladder, MUC II to colon cancers [8].