Formation of erythyroid progenitors

Schematic representation of the formation of erythroid progenitors (BFU-E and CFU-E) from hematopoietic stem cells (HSC) directly or from common myeloid progenitor and multipotent progenitor cells (CMP/MPP). The transcription factors important for the maturation and differentiation of HSC and expansion of the stem/progenitor compartment are indicated on the right, according to whether they are important for primary erythropoiesis in the yolk sac and/or definitive erythropoiesis in the fetal liver and/or bone marrow. Certain growth factors and their receptors, such as stem cell factor (SCF)/KIT and erythropoietin (Epo/EpoR), are important or essential for erythropoiesis, respectively; by comparison, other growth factors, such as IL-3 or GM-CSF, act synergistically with SCF.