MMP9 and head and neck cancer: Several studies demonstrated that sEV-driven metabolic changes promote angiogenesis in acute myeloid leukaemia (AML), colorectal cancer, and head and neck cancer using an HUVEC tube formation assay via different mechanisms such as miR-221-3p transfer in AML, SRSF3-mediated VEGF upregulation in colorectal cancer, and MMP-9 enrichment in head and neck cancer [13,14,15,16].