MMP9 and fibrosarcoma: Since the original identification of galetinase B/matrix metalloproteinase (MMP)-9, as a human leukocyte gelatinase [1,2,3,4], its characterisation as a type V collagenase [5], the observation that malignant tumour cells express an identical enzyme that associates with metastatic behaviour and degrades type IV collagen under certain conditions [6,7,8,9,10] and its subsequent cloning from HT-1080 fibrosarcoma cells [11], research into the physiological and pathological functions of gelatinase B/MMP-9, in contrast to almost all other MMPs, has continued to increase at a steady rate [12,13].