TTF1 and lung adenocarcinoma: There are multiple transcription start sites (TSSs) in agreement with multiple transcript variants encoding different isoforms of NKX2‐1/TTF‐1 (thyroid transcription factor 1); however, the clinicopathological significance of each transcript isoform of NKX2‐1/TTF‐1 in lung adenocarcinoma (LAD) is unknown.