Cebpa ORF(-/-), germline-deleted mice manifest neonatal lethality due to hepatic defects, with marked neutropenia and monocytopenia [19, 30], and Cebpa ORF(-/-) fetal liver cells are also deficient in generating neutrophils and monocytes and manifest increased erythropoiesis [31, 39]. This evidence concerns the gene CEBPA and neutropenia.