GBM–EVs were therefore reported to transfer miR-451 and miR-21 to microglia cells in vitro, stimulating cell proliferation and leading to a decrease in c-Myc expression and consecutive polarisation to a M2 phenotype in the recipient cells, with increased expression of key markers such as IL-6 and tissue inhibitor of metalloproteinases-1 (TIMP-1). Here, TIMP1 is linked to glioblastoma.