MMP9 and neoplasm: MMP-9 and VEGF, proteins that are important for tumor metastasis through extracellular matrix degradation and angiogenesis, respectively, were measured locally in primary tumors and systemically in serum, identifying increased MMP-9 levels at 1, 3, and 6 w p.i. (Figure 3A) and increased VEGF levels at 3 as well as 6 w p.i. (Figure 3B) in the 4T1- compared to the Py230-based intraductal model.