Cleaved Bcl-xL is enriched in stroma-derived exosomes and is present on the exosomal surface. (A) Western blot analysis of L88 cells and exosomes for the antiapoptotic Bcl-2 family members Bcl-2, Bcl-xL, and Mcl-1. (B) Western blot analysis of Bcl-xL in stroma L88, mesenchymal stem cell (MSC), mBMSC, and prostate cancer cell line PC3. (C) Immunoelectron microscopy for Bcl-xL in the exosomal surface of L88 cell–derived exosomes. (D) Fluorescence intensity of L88 cell–derived exosomes bound to beads and stained with Bcl-xL antibody. Exo, exosome.