Several human cancers are still poorly understood at the molecular level. Recently, we discovered a novel gene family, called NBPF for Neuroblastoma BreakPoint gene Family, whose members are localized on chromosome 1 in regions that are often deleted or amplified in various tumor types. On the other hand, there is growing evidence for involvement of several members of the newly defined delta-protocadherin gene family in human cancer. We have ample experience in the structural and functional analysis of these two gene families, and also in the genetic and molecular analysis of human tumors. We propose to seek conclusive evidence for a casual relationship between particular human cancers and deregulations in either NBPF or delta-protocadherin family members. Moreover, we will generate suitable mouse models to extend and confirm our findings in vivo and to serve development of appropriate therapies.