Then, to analyze the interaction between these EMT-related genes on the morphological features of PNENs, we selected four groups: SCLC vs. LCNEC (GSK3B, ITGB1, MAP1B, TCF3, VPSA13, and SMAD2), AC vs. TC (MMP3 and SNAI2), LCNEC vs. AC (MMP3, ITGAV, KRT14, PLEK2, and SNAI2), and SCLC vs. AC (PLEK2, MAP1B, MMP2, SNAI2, SPARC, WNT5A, and ITGA5). This evidence concerns the gene SMAD2 and large cell neuroendocrine carcinoma.