These results suggest that the location of TAMs in CRCs appear to be an important factor in antitumour activation. This concept is further supported by other reports demonstrating that peritumoral macrophages are likely to have less contact with tumour-derived cytokines, and are positioned in less hypoxic areas, indicating that they may display a tumouricidal rather than tumour promoting activity. This model very closely aligns with our data that demonstrates uPARS is a positive prognostic indicator of survival in the invasive front of stage C RCs. These data are further supported by the presence of uPARPT at the same location and stage, which was associated with longer survival than when uPARPT was absent. Collectively, it is possible that the population ofM1 macrophages and/or newly recruited monocytes may represent a higher proportion of macrophages at the invasive front and in peritumoural regions of CRCs, and that uPARS detected by R4 might be expressed by those stroma-associated cells. In fact, a recent study demonstrated that in an experimental model of colitis, uPAR controls the function of intestinal macrophages by reducing inflammatory INCB28060 cytokines and controlling M1 and M2 polarisation. For future studies, simultaneous IHC of monocytes, M1- and M2-polarised macrophages, and R4 on serial CRC TMA sections may further clarify our understanding of the role/s of uPAR in stroma-associated cancer biology. Although uPARE was expressed in a significant number of adjacent non-neoplastic mucosal tissues, we have not considered to use this as an internal standard because it may not be as representative as healthy mucosa, since the histologically normal tissues used in this study were taken from 1�C2cm from the tumour margin. We have recently demonstrated that integrin ���ͦ�6 was expressed in almost all histological normal mucosa. As the integrin ���ͦ�6 is one of key regulators of EMT along with TGF beta1, it indicates that EMT-associated changes are occurring in that tissue. This observation also supported by other types of cancer demonstrated that the expression of EMT markers occur in ��apparently�� histologically normal breast tissue that is located 1cm away from breast cancer tissue margins. In conclusion, we have found that uPARE is associated with poorer RC survival in stage B whilst uPARS is correlated with longer survival in stage C. This indicates that uPAR has an opposite role in different cell types at different tumour locations across RC stages B and C. We have proposed that these functional differences may potentially be related to differences in the MLN4924 uPAR-interactomes present in distinct cell types. In this regard, we have already unequivocally shown uPAR interacts with ��v��6 which is an epithelially-restricted integrin. Therefore, a comprehensive study of the uPAR interactome in different cell types and consequent reactivity of uPAR with various anti-uPAR MAbs is a necessary step towards an understanding of its roles in CRC. Indeed, MAb inhibition of the uPAR-integrin interactome has been recently proposed as a new anti-cancer therapeutic approach and a basis to develop tumour imaging methodologies. Overall, accurate prediction of patient survival based on uPAR expression coupled with a better understanding and targeting of specific uPAR interactomes may lead to the development of novel, personalised companion immunopathology prognostics and anti-metastasis therapeutics. Enzyme promiscuity can function as a starting point in divergent evolution for generating a specific enzyme in the presence of selective stress. A better understanding of catalytic promiscuity can improve our knowledge of protein evolution and ancestry as well as providing new tools for protein engineering and biotechnological applications.