MMP9 and leukemia: In this study, to examine if blood cancer EVs could also induce secretion of MMP9 and IL-6 from monocytes, EVs were isolated from a variety of malignant haematopoietic cells including leukaemia (HG3, I83, K562) and myeloma (U266) by differential centrifugation and iodixanol density flotation gradient (Fig 1).