PLAU and cancer: This is demonstrated by the abundance of clinical evidence citing uPA and uPAR upregulation in the tumour tissue and sera of multiple cancer types, including breast [29,30,31,32], pancreatic [33,34,35], colon [36,37], gastric [38,39], skin [40,41] and ovarian cancers [42,43,44], which is contrasted by the typically absent or low levels of expression in normal and healthy tissues, including those adjacent to the tumour.