The observation that the expression of Gfi1, or Gfi1b, in Runx1−/− deficient HE cells induces the loss of endothelial identity but does not confer hematopoietic potential suggest that RUNX1 also activates the expression of a different set of genes required for blood commitment (Fig. 2). This evidence concerns the gene RUNX1 and hereditary elliptocytosis.