ERBB2 and neoplasm: While negligible levels of cytotoxicity were detected against PHA-stimulated PBLs (i.e., TF-negative controls, data not shown), tumour cell lines expressing high levels of TF (i.e., USPC-ARK-2, USPC-ARK-3 and USPC-ARK-6), regardless of their high or low HER2/neu expression, were found to be highly sensitive to hI-con1-induced antibody-dependant cell death (mean±s.d., 65.6±3.7% range, 57.5–77.0% Figure 3; P<0.001).