As a methodology, SFD is able to reveal well-known proteins in melanoma exosomes that are immune-related and are also surface-expressed proteins, such as CD26 (DPP4), CD44, CALR, B7-H3 (CD276), CSF1, ICAM1, L1CAM, MICB, APOH, TIMP1, and CD39. Here, DPP4 is linked to melanoma.