Fig. 1

Different mechanisms of cell-free miRNA release from cancer cells. miRNAs can be released from cells and enter the bloodstream, urine or seminal fluid either in the form of membrane-enclosed vesicles (i.e., exosomes, microvesicles, apoptotic bodies and large oncosomes) that differ in size and molecular content or vesicle-free forms, where miRNAs are bound to specific RNA binding proteins or packaged in high density lipoprotein complexes. AGO2, argonaute2; NPM1, nucleophosmin 1; MVB, multivesicular body