The catenin p120 (hereafter p120^ctn) was first identified as a Src kinase substrate and subsequently characterized as an Armadillo catenin member of the cell–cell adhesion cadherin–catenin complex. In the past decade, many studies have revealed roles for p120^ctn in regulating Rho family GTPase activity and E-cadherin stability and turnover, events that occur predominantly at the plasma membrane or in the cytoplasm. However, the recent discovery of the nuclear BTB/POZ-ZF transcription factor Kaiso as a p120^ctn binding partner, coupled with the detection of p120^ctn in the nucleus of some cell lines and tumor tissues, suggested that like the classical β-catenin, p120^ctn undergoes nucleocytoplasmic trafficking and regulates gene expression. Indeed, p120^ctn has a classic nuclear localization signal and does traffic to the nucleus. Moreover, nuclear p120^ctn regulates Kaiso DNA-binding and transcriptional activity, similar to β-catenin's modulation of TCF/LEF transcription activity. However unlike β-catenin, p120^ctn does not appear to be a transcriptional activator. Hence it remains to be determined whether the sole role of nuclear p120^ctn is regulation of Kaiso or whether p120^ctn binds and regulates other transcription factors or nuclear proteins.