BMSC-derived exosomes increase MM cell survival and reduce the activation of caspase-3/8/9. 5T33MMvt (A) or 5T33MMvv (B) cells were cultured in serum-free conditions and treated with different amounts of naive or 5T33 BMSC-derived exosomes for 24 (5T33MMvv cells) or 48 hours (5T33MMvt cells). Apoptotic cells were determined using 7-aminoactinomycin D (7-AAD) and Annexin-V staining after treatment. A similar set-up was used to detect apoptosis-related proteins Bcl-2, Bax, caspase-8, caspase-9, and caspase-3 in 5T33MMvt (C) and 5T33MMvv (D) cells after exosome treatment, using western blot. The analysis of β-actin protein was included as a loading control. The pixel densities of proteins were quantified from 3 independent experiments and presented by histograms in the bottom panel. Mean values ± standard deviation for 3 independent experiments are shown. *P < .05; **P < .01; ***P < .001. cas3, caspase-3; cas9, caspase-9; Cl, cleaved; Fl, full-length.