The effects of GF109203X on CD44DL, ADCC, and natural cytotoxicity. Activated LD-PBL were tested for lytic activity in the presence of the indicated concentrations of the PKC inhibitor, GF109203X. CD44DL (upper panel) and ADCC (middle panel) were tested with TNP-MC1 targets, and natural cytotoxicity (lower panel) was measured using K562 target cells. GF109203X concentrations were 2.0 (▵), 0.5 (□), 0.12 (○), and 0 μmol/L (•). (▪) Lysis in the absence of antibody or GF109203X. Similar results have been obtained in five separate experiments.