SMAD4 and pachyonychia congenita: The EMT-related target genes are summarized as follows: (1) TGF-β signaling pathway: TGFβ2 and TGFβR3. Previous studies showed that TGFβ signaling is significantly elevated in PC with Smad4 mutation, resulting in the loss of Smad4-dependent cell growth inhibition and increased Smad4 independent EMT [18].