MMP9 and cancer: In fact, O3 administration was found to lower the peripheral-blood levels of circulating free DNA (cfDNA, i.e., the degraded DNA fragments that in advanced cancer are increasingly released into body fluids), IFN-γ, MPO-DNA complexes, TNF-α, IL-6, HIF-1α, and MMP-9 while increasing p-AMPK and SR-A protein expression in tumour tissues.