TCF4, as known as transcription factor 4 isoform I, is a protein acting as a transcription factor. This protein will bind to the immunoglobulin enhancer mu-E5/kappa-E2 motif. Also, it activates transcription by binding to the E-box (5 -CANNTG-3) found usually on SSTR2-INR, or somatostatin receptor 2 initiator element. This protein is found in the central nervous system, somites, and gonadal ridge during early development. Later in development it will be found in the thyroid, thymus, and kidneys while in adulthood it is found in lymphocytes, muscles, and gastrointestinal system. Recombinant human TCF4, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.