TTF1 and non-small cell lung carcinoma: As an example, H&E can establish the presence of NSCLC, but often expression of two or more of the proteins p40, thyroid transcription factor-1 (TTF-1), cytokeratins 5 & 6, and/or Napsin A are required to clearly classify the cancer as squamous cell carcinoma (SSC) or adenocarcinoma (ADC)9,10.