Our past works have shown that that integrin (avb6) and protease receptor (uPAR) expression are upregulated in colorectal cancer (CRC), allowing us to understand changes associated with the epithelial metastatic phenotype.  Here, we show how immunoprecipitation allows identification of uPAR- and avb6-interacting membrane proteins (i.e., metastasome) and downstream signaling events are linked. We also demonstrate how the metastasome is involved in regulation of cellular invasive characteristics, including the switch of TGFb1 from a suppressive to an aggressive factor in late stage colorectal cancer. Analyses of the precise sites of protein interaction between uPAR and integrin avb6 using a plethora of methods, including  peptide arrays, peptide competition assays, in silico modelling, inhibitory peptide (iPEP) studies and proximity ligation confirm the interaction and suggest interesting biologies that have implications for development of new therapies targeted at this interaction. These studies have developed lead iPEPs and are now focussed on small molecule compounds that antagonise this particular metastasome. Both lynchpin proteins (uPAR and avb6) are independently shown to be poor epithelial prognostic indicators, especially in Stage B rectal cancer. Despite this data, little is known regarding patient outcome when both factors are  co-expressed. We propose a new model for how signal transduction “switches” require pre-formation of a precise membrane interactome composition.  In addition, our recent rectal cancer study demonstrates that uPAR is expressed both in the stromal and/or epithelial compartments (presumably with different interactomes since avb6 is epithelially-restricted) and that high expression in these different compartments results in opposite clinical survival outcomes (high epithelial rectal cancer uPAR levels poorer prognosis; high stromal expression better prognosis). We are exploring if the ratio of these uPAR measurements provides a better overall clinical prognostic indicator.  Collectively, our data demonstrate combination(s) of clinical proteomics and cell biological methods result in deep, comprehensive membrane proteome understanding in cancer, providing a potential new CRC therapeutic target.