MicroRNAs (miRs) are small non-coding RNAs that are 20 to 25 nucleotides in length and regulate expression of entire families of genes. A major source of circulating miRs in cancer patients is believed to be circulating microvesicles (cMV) within biologic fluids such as blood. The transfer of these modifiers of RNA translation from diseased cells into the bloodstream can have broad impacts on disease detection, progression and/or prognosis. The goal of these studies was to determine whether there are differences in miR composition within different subpopulations of cMV based on surface protein composition.