SMAD2 and small cell lung carcinoma: They included: (1) overexpression of GSK3B, ITGB1, MAP1B, TCF3, VPSA13, and SMAD2 in SCLC compared to LCNEC; (2) overexpression of MMP3 in TC and under-expression of SNAI2 in AC; (3) overexpression of MMP3, ITGAV, KRT14, PLEK2, and SNAI2 in LCNEC compared to AC; (4) PLEK2, MAP1B, MMP2, SNAI2, SPARC, WNT5A, and ITGA5 overexpression in SCLC compared to AC.