Recent investigations on the mechanism of anti-tumour action of these anti-ErbB2 immunoagents have indicated that Erb-hcAb induces the homodimerisation of ErbB2, which leads to its downregulation and lysosomal degradation, and induces ADCC (De Lorenzo et al, 2005); the anti-tumour action of ERB-hRNase instead depends on its ribonuclease activity, which is exerted in the cytosol (De Lorenzo et al, 2007b). Here, ERBB2 is linked to neoplasm.