Selection of sensitive antibodies and optimization of protocols to the best signal-to-noise ratio may in some cases hamper the “diagnostic specificity.” E.g., in lung cancer, reports have found that thyroid transcription factor-1 (TTF-1) clone 8G7G3/1 was positive in 1 % of squamous cell carcinomas, and 65–77 % of lung adenocarcinomas, whereas TTF-1 clone SPT24 was positive in 17 % of squamous cell carcinomas and 72–84 % of adenocarcinomas [14]. This evidence concerns the gene NKX2-1 and lung cancer.