Granulopoiesis can be rescued inC/EBPα−/− mice by exogenous GM-CSF or IL-3 [2], or by theexpression of C/EBPβ from the C/EBPα locus [5].C/EBPβ−/− mice, in contrast, exhibit normal numbersof neutrophils in the steady-state, but fail to mount neutrophilias in response toinfection or cytokine treatment, implicating C/EBPβ as a regulator of emergencygranulopoiesis [2].Growth factors elicited during infections are thought to reduce C/EBPαexpression in GMP while increasing C/EBPβ expression, and thereby focusingdifferentiation towards neutrophils while elevating rates of proliferation [2]. This evidence concerns the gene CEBPB and infection.