TBX4 and squamous cell lung carcinoma: As expected, results showed a significant decrease of TBX2, TBX3, TBX4 and TBX5 expression in lung squamous cell carcinoma tissues compared to paired normal lung tissues, which further supported our hypothesis (Fig. 5).The proteins of TBX2,TBX3,TBX4,TBX5 were medium expressed in lung squamous cell carcinoma tissues, whereas not or low expressions of them were found in normal lung tissues.