TP63 and lung adenocarcinoma: Previously, research has shown that the expression level of surface markers like TTF1 and TP63 was similar in lung adenocarcinoma cell lines and lung squamous cell lines, which was significantly different from clinical histopathology results which show that lung squamous was negative for TTF1 and approximately 100% positive for TP63, whereas lung adenocarcinoma was 70–80% positive for TTF1 (8).