SP1 and familial pancreatic carcinoma: Third, MACC1 is not the only regulator of MET, and there are many proteins other than MACC1 that can directly regulate MET expression (e.g., HIF1, SP1, AP1, and Ets-1) [38–41], suggesting that MACC1 may not be a predominant regulator of MET in pancreatic cancer.