GPRC5A and urinary bladder cancer: In 2008, Smalley et al. compared the protein profile of urinary exosomes between patients with bladder cancer and healthy controls and identified eight urinary exosomal proteins as potential biomarkers for bladder cancer, including five proteins associated with the EGFR pathway, the alpha subunit of Gs protein, resistin, and retinoic acid-induced protein 3 [40].