FRAT1 and FRAT2 were originally characterized as proteins frequently rearranged in advanced T cell lymphoma, and they have since been identified as proto-oncogenes involved in tumorigenesis. These proteins share significant homology with the Xenopus glycogen synthase kinase-3 (xGSK-3) binding protein, which is designated GBP and is essential for the formation of the dorsal-ventral axis during embryonic development. Establishment of these embryonic axes is mediated by the Wnt intracellular signaling pathway. Wnt signaling is regulated in part by the activity of GSK-3, which phosphorylates and thereby facilitates the degradation of ?catenin. GBP binds to GSK-3 and inhibits this phosphorylation, resulting in the accumulation of ?catenin and the subsequent transcription of Wnt target genes. Like GBP, FRAT2 has been shown to bind xGSK-3, suggesting that FRAT1 and FRAT2 may be GSK-3 regulatory proteins.