MSLN and pancreatic intraductal papillary-mucinous neoplasm: However, it is not clear at which moment of cancer development the MSLN expression begins: while the pancreatic intraepithelial neoplasia does not show MSLN expression [42], MSLN is observed in the intraductal papillary mucinous neoplasms [44], with a higher frequency in the invasive lesions [45,49].