The specificity of interaction between MD.45-HER/ζ hybridoma CTL and HER-2/neu expressing tumour cell lines or primary tumour cells was also confirmed by the fact that an anti-HER-2/neu MAb when present throughout the 24 h incubation period substantially blocked IL-2 secretion (range of % inhibition: 64–90) (Table 1). This evidence concerns the gene ERBB2 and neoplasm.