Allegedly established from the peripheral blood of a 40-year-old man with acute monoblastic leukemia (AML M5) at relapse in 1982; however, recent new data suggest derivation from T-ALL (acute lymphoblastic leukemia): (1) T-ALL-associated gene expression signature (Andersson et al., Leukemia 19: 1042-1050, 2005); (2) own FISH analysis confirming t(1;7) effecting TAL1-TRB@ (TAL1-TRB) fusion; (3) own reanalysis of the immunoprofile