Catenin beta Protein

?-catenins are cytoplasmic proteins that are ubiquitously expressed. These proteins associate with E-cadherin at cellular junctions (1). ?-catenin interacts with TCF and LEF transcription factors and is an essential member of the Wingless-Wnt signal transduction pathway. The adenomatous polyposis coli (APC) tumor-suppressor protein, together with Axin and GSK3?, form a Wnt-regulated signaling complex that mediates phosphorylation-dependent degradation of ?-catenin by the proteasome. APC and Siah-1 mediate a novel ?-catenin degradation pathway linking p53 activation to cell cycle control. Activating mutations in the human ?-catenin gene have been found in human colon cancer and melanomas (2).