CAMP (Cathelicidin AntiMicrobial Peptide; also18kD cationic antimicrobial protein, CAP18, LL37, FALL39 and HSD26) is a member of the cathelicidin family of proteins. It is widely expressed, being found associated with neutrophils, bronchial epithelium, renal tubule epithelium, activated keratinocytes, gd T cells, monocytes, NK cells, colonic epithelium and the stratum basale of nonkeratinized epithelium found in the vagina and oral cavity. CAMP has marked antimicrobial activity against both Gm+ and Gm- bacteria, and acts as a chemoattractant for neutrophils, monocytes and mast cells. CAMP is synthesized as 170aa preproprecursor. It contains a 30aa signal sequence, a 103aa, 14kD prosegment (aa31-131) and a 4-5kD, 37aa (aa134-170) C-terminal mature fragment (LL37) or 39aa (aa132-170) C-terminal mature fragment (FALL39). In neutrophils, the 18-19kD proprecursor is stored in granules, where, upon activation, it is enzymatically cleaved and released. While both the prosegment and C-terminal fragments possess antimicrobial activity, the prosegment also shows protease activity, while the C-terminal fragment also shows chemotactic activity. The prosegment may form homodimers, while the C-terminal fragment (LL37) is reported to form homotetramers. Over aa141-170, human CAMP shares only 50% and 57% aa sequence identity with mouse and rat CAMP, respectively.