Model of the functional requirements for GFI1/GFI1b and RUNX1 during yolk-sac EHT. RUNX1 is required for both the change in morphology and acquisition of hematopoietic competence (cells turning red). GFI1/GFI1B are essential for the change in morphology, and additional unknown transcriptional targets of RUNX1 are required for acquisition of full hematopoietic competence.