NKX2-5 and acute lymphoblastic leukemia: Besides genetic mutations, gene expression profiling in patients with T-ALL has revealed aberrant expression of a diverse group of transcription factors such as LYL1, LMO1, LMO2, TAL1, TLX1, TLX3, HOXA, NKX2.1, NKX2.2, NKX2.5, MYC, MYB, and SPI1 in distinct T-ALL subtypes (7, 11).