As described above, autophagy has a dual role: in pancreatic ductal adenocarcinoma cells, TGF-β1 induced autophagy in SMAD4-positive cells and inhibited migration by reducing nuclear translocation of SMAD family member 4 (SMAD4), whereas, in SMAD4-negative cells, migration was increased through mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK)[42]. The gene discussed is SMAD4; the disease is pancreatic ductal adenocarcinoma.