MMP9 and colorectal cancer: Accordingly, in a study on a transplantable murine colorectal cancer (CRC) model, the authors found corresponding changes between serum IL-17A levels and the FACS-determined prevalence of CTCs at different stages of disease; moreover, IL-17A promoted angiogenesis and metastasis in vivo, as well as matrix metalloproteinase 9 (MMP9)-dependent invasiveness of tumor cells in vitro [47].