Proposed model for neutrophil recruitment by increasing concentrations of NAP-2 arising during inflammation. CTAP-III released from activated platelets is proteolytically converted into NAP-2 by neutrophils attached to a thrombus. Low dosages of NAP-2, formed in the initial phase of CTAP-III processing, attract further cells from the periphery through CXCR-2. Increasing dosages of NAP-2 accumulate in the progress of processing and cause the downregulation of CXCR-2. Further migration of the cells to the finally high concentrations of NAP-2 is mediated through CXCR-1.