Cytokine production does not account for the in vivo effects of MBECs. (A) ELISAs performed on MBEC-CM (1 ×) revealed significantly increased mean concentrations of VEGF, PDGF-AA, SDF-1, and IL-6 compared with all other cytokines that were measured (*P < .03 for multiple comparison test). Standard errors about the mean are represented by error bars. (B) C57Bl6 mice were irradiated with 1050 cGy and subsequently treated with 5 days of intraperitoneal administration of VEGF, PDGF-AA, SDF-1, or IL-6 or the combination of VEGF, PDGF-AA, SDF-1, and IL-6, beginning at 2 hours after irradiation. The percent survival in each treatment group is shown as compared with control, irradiated mice. No animals in any group survived beyond day +28.