Furthermore, NO promotes tumour cell invasion in the C3L5 murine mammary adenocarcinoma model by altering the balance between the expression of matrix metalloproteinase-2 (MMP-2) and it's tissue inhibitors-2 and -3 (TIMP 2 and TIMP 3) (Orucevic et al, 1999). This evidence concerns the gene MMP2 and neoplasm.