PKM and pancreatic ductal adenocarcinoma: Since in human pancreatic ductal adenocarcinoma (PDAC) HIF-1α expression highly correlates with tumor size and poor prognosis [31] it will be a demanding task to dissect the different signaling states and the potential of feed-back signaling loops which may be of great importance for therapeutic targeting of pancreatic tumors using PKM2 inhibitors currently under intense development.