An apical lymph node was defined as the most proximal node found within 1 cm of the vessel ligation at the apex of a vascular pedicle. Tumours were histologically classified as low-, average-, or high grade malignancy. Grade was assessed taking into account the degree of differentiation and anaplasia, the nature of the tumour margin and the presence and prominence of vascular invasion. In advanced stage tumours the proportion of involved lymph nodes was calculated as a percentage of the total number of nodes harvested. Before 2002 over 90% of specimens were reported on or reviewed by a single pathologist. All pathology features analysed were looked for in every specimen and their presence or absence recorded explicitly. There were no missing data on any variable. Although the prognostic relevance of uPAR in cancer has been extensively studied, significant discrepancies have rendered much of the work inconclusive. Two major issues remain unresolved: firstly, the discrepancy regarding the cell types where uPAR is overexpressed, and secondly, the prognostic relevance of uPAR in different cell types and different stages of tumour MLN4924 Metabolic Enzyme/Protease inhibitor progression. In this study we have addressed the first paradox by demonstrating that uPAR expression in different cell types can be detected using two epitopespecific anti-human uPAR MAbs #3937 and R4. These antibodies delineated between uPARE and uPARS expression in RC tissues, showing antigen expression could be differentially detected in different cell types and tumour locations in the same RC tissues. Upon examination of uPARE and uPARS from 349 stage B or C RC tissues, we were able to decipher the second controversy, revealing that elevated uPARE in both the central region and invasive tumour front adversely correlated with stage B overall survival, whereas elevated uPARS at the invasive front favourably correlated with stage C overall survival. The recognition of different uPAR epitopes by different antibodies is an important factor to be considered, not only for detection in different cell types but also for determination of the potential clinical prognostic relevance of uPAR. There are multiple anti-uPAR polyclonal antibodies and MAbs which have been developed and studied extensively in clinical applications. Of these, MAbs #3937 and R4 are most frequently used for uPARE and uPARS detection respectively and stand at the centre of disparate CP-690550 purchase results obtained by different laboratories. Several factors may explain the specificity of these different antibodies, the primary one being binding to different ��available�� epitopes reflecting potentially diverse roles of uPAR in each cell type. As uPAR has 42 known interacting partners, it is also possible that the antibody epitopes may be masked by other uPAR interacting partners in different cell types. The multifunctional nature of uPAR is a function of its interactome, and therefore uPAR detected by different epitope-specific MAbs may have different interacting partners, which may reflect divergent functions in discrete cell types.