Transcription factor that binds DNA in a sequence-specific manner (PubMed:2010090). Participates in the Wnt signaling pathway (By similarity). Activates transcription of target genes in the presence of CTNNB1 and EP300 (By similarity). PIAG antagonizes both Wnt-dependent and Wnt-independent activation by LEF1 (By similarity). TLE1, TLE2, TLE3 and TLE4 repress transactivation mediated by LEF1 and CTNNB1 (PubMed:11266540). Regulates T-cell receptor alpha enhancer function (PubMed:19653274). Required for IL17A expressing gamma-delta T-cell maturation and development, via binding to regulator loci of BLK to modulate expression (By similarity). Acts as a positive regulator of odontoblast differentiation during mesenchymal tooth germ formation, expression is repressed during the bell stage by MSX1-mediated inhibition of CTNNB1 signaling (By similarity). May play a role in hair cell differentiation and follicle morphogenesis (By similarity). {ECO:0000250|UniProtKB:P27782, ECO:0000269|PubMed:11266540, ECO:0000269|PubMed:19653274, ECO:0000269|PubMed:2010090}. [Isoform 1]: Transcriptionally activates MYC and CCND1 expression and enhances proliferation of pancreatic tumor cells. . [Isoform 3]: Lacks the CTNNB1 interaction domain and may therefore be an antagonist for Wnt signaling. . [Isoform 5]: Transcriptionally activates the fibronectin promoter, binds to and represses transcription from the E-cadherin promoter in a CTNNB1-independent manner, and is involved in reducing cellular aggregation and increasing cell migration of pancreatic cancer cells. . This is the function of ENSG00000138795 (LEF1, lymphoid enhancer binding factor 1).