The production of MMPs has been monitored preclinically, with a probe cleaved by MMP-2 and MMP-9 giving an increase in PAI signal upon cleavage in preclinical models of follicular thyroid carcinoma (Levi et al., 2013), which express high levels of MMP-2, MMP-7 and MMP-9 compared to benign thyroid adenomas. Here, MMP9 is linked to thyroid gland follicular carcinoma.