TAL1 and acute leukemia: Runx1 is expressed in the hematopoietic precursors of the yolk sac (North et al., 1999; Samokhvalov et al., 2007) where it is a direct target of the master regulator of hematopoiesis SCL/TAL1 (Stem cell leukemia/T‐cell acute lymphoblastic leukemia 1) (Landry et al., 2008).