MMP9 and cancer: MCs are the important source of pro-angiogenic factors and also influence the progression of cancer by modulating the cancer microenvironment by producing matrix metalloproteinases (MMP-2, MMP-9), and proteases (tryptase and chymase) that play a central role in ECM degradation and allow cancer cells to invade the microenvironment and metastasize to diverse locations (16).