In conclusion, our experiments clearly and consistently indicate that IGF-I overexpression in the osteoblast lineage does not contribute to enhancement of repair of bone erosions or syndesmophyte formation during experimental arthritis, although IGF-I has clearly a role in bone metabolism, our data concord to indicate that it is not a major determinant of osteoproliferation in inflammatory arthritis. The gene discussed is IGF1; the disease is Arthritis.