1. An assay comprising the steps of: (a) providing a live cell derived from a subject suspected of having cancer, wherein the live cell having a plurality of a Eph receptor on the cell surface, said live cell being capable of activating Eph receptor redistribution on the surface of the cell, the Eph receptor capable of binding a ligand, whereupon binding of the ligand by said plurality of a Eph receptor activates receptor redistribution and results in a detectable pattern of the plurality of Eph receptors distributed on the surface of the cell; (b) providing a physical context wherein the physical context further comprises a supported lipid bilayer having the ligand displayed or attached thereto; (c) contacting said live cell to the ligand attached to said physical context; (d) detecting and quantifying the pattern of Eph receptor redistribution and activation of said pattern of Eph receptor distribution on the surface of the cell where said live cell is attached, wherein the quantifying step (d) further comprises determining a normalized radial transport or radial distribution score of the pattern of Eph receptor redistribution; (e) correlating said detectable pattern of Eph receptor redistribution to a signature for aggressive cancer cells or metastatic cancer cells; and (f) providing a diagnosis of the subject's condition based on said correlation to the aggressive or metastatic cancer cells and administering a therapeutic appropriate to treat such cancer cells in said subject.