Hitherto, model T-ALL cell lines have been described for TLX1 (ALL-SIL), TLX3 (HPB-ALL, DND-41), NKX2-5 (CCRF-CEM, PEER), NKX3-1 (HSB-2, JURKAT, MOLT-14, PER-117, PF-382, RPMI-8402), and MSX1 (LOUCY, PER-117) [7,19–22]. The gene discussed is TLX3; the disease is acute lymphoblastic leukemia.