Leng and colleagues based their study on a spontaneous mouse breast cancer model (using transgenic mice carrying the mutant form of ErbB2(V664E) driven by the mammary-specific promoter MMTV), in which they observed significantly delayed lung metastasis, and lowered MMP9 expression and activity, in Lcn-2-deficient mice. The gene discussed is ERBB2; the disease is breast carcinoma.