MMP9 and neoplasm: For example, fibroblasts in the irradiated stroma can secrete tumour growth factor β1 (TGF-β1) and reactive oxygen species (ROS) that have an impact on the phenotype of keratinocytes, on the process of epithelial-mesenchymal transition (EMT) and on the function of local immunocytes; and can secrete matrix metalloproteinases 9 (MMP 9) and beta fibroblast growth factor (bFGF) which can mediate vascular remodelling and influence the composition of the tumour inflammatory cell infiltrate.