TAL1 and T-cell acute lymphoblastic leukemia: T cell acute lymphoblastic leukemia (T-ALL) is a cancer of early thymocytes and is characterized by recurrent chromosomal rearrangements that activate oncogenic transcription factors such as TAL1/2, LMO1/2/3, NKX2.1/2.2, TLX1, TLX3, or HOXA.