GSTM2 and urinary bladder cancer: Interestingly, the decrease in levels of protein biomarkers, including adipocyte-type fatty acid-binding protein (aFABP), glutathione S-transferase μ (GST μ), and 15-hydroxyprostaglandin dehydrogenase (PGDH), as well as cytokeratin 13 (CK13), has been described in high-grade human bladder cancer [29, 30].