MPL and infection: Acute IFN-γ exposure has been shown to induce both myelopoiesis and granulopoiesis in response to an infection, but chronic IFN-γ exposure has been shown to cause HSPC arrest through the binding and occlusion of the HSPC pro-survival factor thrombopoietin (TPO) to its cognate receptor c-MPL (40, 41).