Assessment of the clinical significance of antigenic and functional levels of α1-proteinase inhibitor (α1-Pi) in infiltrating ductal breast carcinomas

► The clinical significance of immunoreactive and functional levels of α1-Pi was assessed. ► 2-DE western blot/MS was used to explore α1-Pi alterations with regard to disease progression. ► A role for α1-Pi in node metastatic development in breast cancer is suggested. ► Both α1-Pi levels and activity could be the source of complementary clinical information.