CSF2 and neutropenia: Hematopoietic growth factor cytokines, on the other hand, comprise colony-stimulating factors (CSF) including granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF), which are employed as immunostimulants to treat neutropenia (Metcalf, 2010) and are produced since 1991 in E. coli (CSF filgrastim) and S. cerevisiae (GM-CSF sargramostim) (Table 1).