Tag7 on CTLs interacts with Hsp70 on K562. (A-C) Streptavidin-peroxidase blotting of biotinylated products resolved by PAGE after coincubation and irreversible cross-linking of (A) CTLs with labeled soluble Hsp70, (B) surface-labeled CTLs with K562, and (C) CTLs with surface-labeled K562 followed by adsorption of membrane material on Sepharose-coupled rabbit polyclonal antibodies (Ab-Seph; antigen specified under the lanes). (D) The same procedure performed after reversible cross-linking of surface-labeled CTLs with K562 (left), and CTLs with surface-labeled K562 (right); the complex was cleaved during PAGE sample processing.