These results of TSS‐level expression of NKX2‐1/TTF‐1 revealed that LAD cells use at least 80% of NKX2‐1 TSSs, suggesting that each TSS and transcript isoform could play a distinct role in lung tumourigenesis, which contributes to the degree of heterogeneity of tumours. This evidence concerns the gene TTF1 and neoplasm.