In the previous studies, ERK signaling was identified to be responsible for the pro-autophagy potential of TGF-β1 in ovarian carcinoma and SMAD4-negative pancreatic ductal adenocarcinoma [42, 43], which was not observed in our study (Additional file 1: Fig. S2). This evidence concerns the gene SMAD4 and pancreatic ductal adenocarcinoma.