CD9 and melanoma: Yamada et al., 2013 used anti-CD9 antibodies coupled with magnetic beads for exosome isolation from cattle milk. Tumor-derived exosomes, which are actively secreted by tumor cells, are a potential source of cancer biomarkers. Immunoaffinity-based isolation of melanoma cell-derived exosomes was performed on the plasma of patients using a specific antibody for the CSPG4 epitope, which is specifically expressed in melanoma cells (Sharma et al., 2018).