Wnt signaling orchestrates gene expression in a plethora of processes during development and adult cell homeostasis via the action of nuclear b-catenin. Yet, little is known about how b-catenin generates context-specific transcriptional outcomes. Addressing this knowledge gap is pivotal since neoplasia of the colorectal epithelium begins with aberrant Wnt/b-catenin signaling and broadly targeting the Wnt pathway can lead to undesirable consequences. We have previously identified the developmental transcription factor TBX3 as a tissue-specific component of the Wnt/b-catenin nuclear complex during mouse forelimb development. Here, we screen for TBX3-interacting nuclear proteins in HEK293T cells by performing BioID followed by mass spectrometry.