an assay device for determining the presence of analytes in a cell lysate comprises a porous support member and a plurality of binding reagents arranged and immobilized at multiple reaction sites on the support member . the binding reagents are selected and arranged to assess the status of a selected cellular signal transduction pathway / protein - protein interactive network . in a further aspect , a method for assessing the status of a signal transduction pathway comprises generating a lysate of cells , the lysate retaining one or more pathway molecules present in one or more states and the pathway molecules reflecting signal transduction events taking place in the cells . the method further includes applying the lysate to an immobilized series of binding reagents which can discriminate the pathway molecules and their states . binding events between the pathway molecules and the binding reagents are identified and the state of the selected signal pathway is determined .