NRG1 and pancreatic ductal adenocarcinoma: Indeed, inhibition of HAS2 upon treatment with its specific inhibitor 4-methylumbelliferone (4-MU, also known as hymecromone), has proven successful in reducing tumour stroma in pancreatic ductal adenocarcinoma (PDAC) [72, 73], which also shows high expression of NRG1 [24].