Half of the FasL-Fas cytotoxicity requires Tag7-Hsp70 interaction. (A) Effects of Tag7 blocking on CTL (30-minute preincubation) with antibodies, rHsp70, its peptide-binding domain (PBD; aa 385-539), or 14-mer peptide (aa 450-463); ineffectiveness of the Hsc70-derived 14-mer analog; and the effect of removing the Hsp-exposing targets. (B) Effects of Hsp70 blocking on K562 (30-minute preincubation) with antibodies, rTag7, and its tryptic peptides (TPs); ineffectiveness of anti-CD94; and the effect of removing the Tag-bearing CTLs; and (C) Cytotoxicity of 4-day LAK culture (containing NK cells) and the effects of antibodies. All data are presented as means (± SEM) in at least 5 independent assays.