Schematic model of myeloid differentiation showing alterations induced by lack of Pbx1.

Semicircular arrows represent self-renewal divisions. Solid lines represent developmental pathways spared by absence of Pbx1 while dashed lines denote affected pathways. Bars beneath the schematic indicate relative levels of various progenitor populations. The lineal relationships of BFU-E and CFU-E with FL MEP have not been experimentally determined and may not be linear as shown.39 Gr indicates granulocyte; Mo, monocyte; Pl, platelet; Er, erythrocyte; RBC, red blood cell; ?, uncertain effect on transition of HSCs to CMPs.