The CXCR2 receptor could mediate chemotaxis and degranulation of neutrophils along with CXCR1, via interleukin-8 (IL-8) a proinflammatory chemokine with the CXC motif. In addition, in a model of arterial injury, CXCR2 can improve endothelial recovery, and also seems to be important in recruiting endothelial progenitor cells to injured vessels. CXCR2 is activated by a plethora of ligands: GROa, b, g, neutrophil-activating peptide, granulocyte chemotactic protein-2 and keratinocyte derived chemokine (CXCL1). CXCR2 is expressed in different brain regions, in the lung and spleen and other regions. ATTO dyes are characterized by strong absorption (high extinction coefficient), high fluorescence quantum yield, and high photo-stability. The ATTO-488 label is analogous to the well known dye fluorescein isothiocyanate (FITC) and can be used with filters typically used to detect FITC.