Yan et al demonstrated that NGAL is capable of protecting MMP-9 from degradation in a dose-dependent manner and thereby preserving MMP-9 enzymatic activity in vitro system by employing recombinant human MMP-9 and NGAL, as well as in a cell culture system in which NGAL was overexpressed in MDA-MB-231 human breast carcinoma cells. This evidence concerns the gene LCN2 and breast carcinoma.