CYLD in ubiquitin signaling and tumor pathogenesis.

Absence of CYLD, which encodes a deubiquitinating enzyme, causes an inherited disease characterized by benign skin tumors. In this issue of Cell, Massoumi et al. (2006) show that CYLD deubiquitinates the coactivator Bcl-3, thereby preventing its translocation into the nucleus, where it normally interacts with NF-kappaB and activates transcription of proliferation genes in response to growth signals.