The T-bet model was developed by Laurie H. Glimcher at Harvard University. The model was creeated by targeting the Tbx21 gene in TC-1 ES cells and injecting the targeted cells into blastocysts. Resultant chimeras were backcrossed to C57BL/6J for one generation and then backcrossed to BALB/cJ for nine generations.. Taconic received stock in 2004. The line was backcrossed to BALB/cJBom for embryo transfer derivation (N10). The colony was maintained through incrossing homozygous mice.