Inhibition of TGF-β1 Receptor Signaling Reverses Exosome-Mediated Effects on CML Cells. (a) Cell growth was evaluated by BrdU assay. LAMA84 cells were incubated for 72, 96 hours, or 1 week, with increasing doses of LAMA84-exosomes (10–20 μg/ml) plus 10 or 20 μM of SB. The values were plotted as a percentage of the control (untreated cells); each point represents the mean ± SD of three independent experiments. (b) Colony formation assay shows that the co-treatment of LAMA84 with 10 or 20 μg/ml of exosomes plus 10 or 20 μM of SB reverses exosome-mediated increase of LAMA84 colonies area (** p ≤ 0.01; ***p ≤ 0.001). (c) Western blot analysis shows that treatment of LAMA84 with 10 μg/ml of exosomes plus 10 μM of SB for 72 or 96 hours decreases the phosphorylation of ERK, Akt and SMAD 2/3 without altering total protein level. The co-treatment with SB reverses exosome-mediated decrease of the pro-apoptotic molecules (BAD, BAX) as well as the increase of the anti-apoptotic proteins (BCL-xl, BCL-w, survivin).