Another group of T-cell acute lymphoblastic leukemia (T-ALL)-associated oncogenes are homeobox genes and includes members of the NK-like family, TLX1/HOX11, TLX3/HOX11L2 and NKX2-5/CSX [11-13], and of the clustered homeobox genes, HOXA5, HOXA9, HOXA10 and HOXA11 [14,15]. Here, HOXA9 is linked to acute lymphoblastic leukemia.