In the last years, we identified idiotype-specific peptides for the Ig-BCR of B cell tumors, named “Id-peptides”, that showed the following properties: a) binding to tumor target cells with high specificity and sensitivity, both in vitro and in vivo; b) internalization into target tumor cells by a BCR-mediated endocytosis; c) specific delivering of a cargo protein into target tumor cells [10,11]. This evidence concerns the gene BCR and neoplasm.