The HAI-2 species with N-glycan branching appears to be mature HAI-2, which is intracellularly localized most likely in the secretory vesicles/granules in mammary epithelial cells and a proportion of which is translocated to the extracellular face of the plasma membrane where the HAI-2 species can inhibit matriptase in breast cancer cells. This evidence concerns the gene ST14 and breast carcinoma.