In preparation for Western blots, exosome fraction #4 was concentrated by centrifugation on a 100 K Amicon Ultra 0.5 mL centrifugal filter (EMD Millipore, Billerica, MA, USA) at 5000 × g. Western blots were performed as previously described [12 (link)]. PVD membranes were incubated overnight at 4 °C with various antibodies (Abs) as indicated below. Exosomes (10 μg protein) were loaded in each lane and tested for the presence of exosome markers, including markers related to hematopoiesis, leukemia blasts markers, and Leukemia Associated Antigens (LAAs) as previously described [12 (link)]. The following Abs were used: anti-TGF-β1 (Cell Signaling, #3711, 1:1000); anti-TNF-a (Cell Signaling, 3707S, 1:1000); anti-TSG101 (Thermo Fisher, PA5–31260, 1:500); anti-EPOR (R&D, MAB307, 1:500); anti-CD26 (R&D, AF1180, 1:500); anti-CLL-1 (R&D, AF2946, 1:2000); anti-CD34 (Santa Cruz, sc-7045, 1:500); and anti-CD33 (Thermo Fisher, WM53, 1:500). Band intensities on exposed films were quantified using Image J software (NIH, USA). The examined band intensity was normalized to the intensity of TSG101 used as a marker of the exosome endocytic origin. The integrated pixel value was determined for each protein band by multiplying image intensity and band area after subtracting the mean background value.