G-CSF and GM-CSF have been demonstrated to improve neutropenia induced by cancer therapy, and recent advances have yielded filgrastism (a G-CSF produced by recombinant DNA technology), pegfilgrastim (a PEGylated form of the G-CSF analogue filgrastim), and sargramostim (a recombinant GM-CSF), which are currently under study as radiation countermeasure agents [198]. This evidence concerns the gene CSF3 and neutropenia.