sentences:  The first is that there are various inactivating nucleotide variations in the human counterpart of the enhancer element that regulates LPS/IFNγ induced expression of the mouse NOS2 gene.The second is because of the absence of a nuclear factor in human macrophages that is required for optimum expression of gene NOS2 (LPS-inducible nuclear factor-kappa B/Rel complex).It is assumed that the difficulty in verifying NOS2 is due to a much more tightly controlled expression in human AMs as compared to that in the rodent AMs.