In preclinical model and in clinical samples, it was demonstrated that lipocalin-2 could protect the degradation of MMP-9 by forming the lipocalin-2/MMP-9 complex, which can enhance the enzymatic activity of MMP-9 and facilitate the tumor growth through promoting its invasion of adjacent tissues or metastasis to distal organs [9-11]. The gene discussed is MMP9; the disease is neoplasm.