identified 307 proteins in urinary exosomes of BC patients and control patients by mass spectrometry, among which 8 proteins showed increased expression of 38 proteins in BC exosomes, while 5 proteins associated with the epidermal growth factor receptor pathway, the alpha subunit of GsGTP binding protein, Resistin, and retinoic acid‐induced protein.99 Here, RETN is linked to breast cancer.