CXC chemokines are characteristieally heparin—binding proteins. On a structural level, they have four highly conserved cysteine amino acid residues, with the first two cysteines separated by one noneonserved amino acid residue, hence the name CXC (14>). Although the CXC motif distinguishes this family from other chemokine families, a second structural domain within this family dictates their angiogenic potential. The NHZ—terminus of the majority of the CXC chemokines contains three amino acid residues (Glu-Leu—Arg: the “ELR” motif) that precede the first cysteine amino acid residue of the primary structure of these cytokines (4). The family members that contain the “ELR” motif (ELR+) are potent promoters of angiogenesis (4). In contrast, interfcron—inducible members of the family that lack the ELR motif (ELRf) are potent inhibitors of angiogenesis (4). On a struetural/functional level, the CXC chemokine family is an unique family of eytokines due to their ability to behave in a disparate manner in the promotion and inhibition of angiogenesis relevant to aberrant vascular remodeling in fibroproliferative disorders.