Synthesis of alpha defensins takes place in neutrophil precursor cells, the promyelocytes, in the bone marrow. Pro HNP1-4 are cleaved in the Golgi body, with HNP-2 being derived from cleavage of the N-terminal amino acid from HNP-1 or HNP-3. The defensin propiece is not only important for correct sub-cellular trafficking and sorting but also inhibits HNP activity (Valore et al. 1996, Wu et al. 2007). The resulting mature peptides are sorted to primary neutrophil (azurophil) granules for storage (Valore & Ganz 1992, Harwig et al. 1992, Cowland & Borregaard).