MAPK1 and pancreatic neoplasm: Further, in pancreatic tumours displaying either SMAD4 deletions or SMAD4 under-expression, ligand stimulation of the TGF-β pathways activates non-canonical pathways including the MAPK, p38/JNK, and PI3K-mTOR pathways which can function independently of SMAD signalling [33, 36, 37].