Transcription factor 4 (TCF4), also known as SEF2, ITF2, E2-2, and ME2, binds to the immunoglobulin enchancer Mu-E5/KE5-motif. Involved in the initiation of neuronal differentiation. Activates transcription by binding to the E box (5'-CANNTG-3'). Binds to the E-box present in the somatostatin receptor 2 initiator element (SSTR2-INR) to activate transcription By similarity. Human TCF4 mRNA expression is particularly high in the brain. Usage of numerous 5' exons of the human TCF4 gene potentially yields in TCF4 protein isoforms with 18 different N-termini. In addition, the diversity of isoforms is increased by alternative splicing of several internal exons. Some isoforms contain a bipartite nuclear localization signal and are exclusively nuclear, whereas distribution of other isoforms relies on heterodimerization partners. Preferentially binds to either 5'-ACANNTGT-3' or 5'-CCANNTGG-3'.TCF4 has several splicing isoforms that are expressed differentially in tissues and during cancer progression(15547706, 12796377). The scopel of molecular weight of several isoforms is about 60-90 kDa (21789225).