A method for detecting cells having granules expressing G protein coupled receptor-associated sorting protein 1 (GASP-1) or a fragment thereof is provided. The detection method may comprise: (a) contacting the cells with an effective amount of a binding protein, wherein the binding protein comprises an antigen binding fragment that specifically binds GASP-1; and (b) identifying cells having granules bound to the binding protein. The GASP-1 granules may be in the cytosol or on the surface of the cells. Also provided are methods for producing T-cells comprising a chimeric antigen receptor, anti-GASP-1 antibody or a bi-specific binding protein. Further provided are methods for treating GASP-1-mediated to disease or inactivating exosomes, microvesicles or oncosomes.