(17) analyzed 55 urine samples (27 bladder cancer, 14 healthy control, and 14 benign samples) by nano-HPLC−ESI−MS/MS and identified 146 differential proteins, and PLK2 was ultimately selected as a biomarker for bladder cancer (sensitivity 80.0%, specificity 64.0%). The gene discussed is PLK2; the disease is urinary bladder carcinoma.