PAK1 and renal pelvis/ureter urothelial carcinoma: In recent years, many potential prognostic tissue biomarkers have been investigated in UTUC including those involved in cell differentiation (Ki67, CDCA5, PAK1, INHBA, PTP4A3), cell cycle regulation (PAK1, Bcl-xL) and antitumoral immunity such as CD204+ macrophages [22].