To ascertain whether the development of β-cell tumours could be accelerated by the somatic delivery of factors previously reported to promote tumor progression in RIP-Tag mice, we infected RIP-Tag; RIP-tva bitransgenic mice with RCASBP vectors that carry cDNA encoding dnE-cad, a mutant protein lacking the extracellular, adhesion-mediating domain of cadherin 1 [21]. The gene discussed is CDH1; the disease is neoplasm.