Table 2.

Genetically altered mouse models to evaluate local IGF-I actions in bone

Model	Promoter used	IGF-I alteration	Skeletal phenotype	Ref.
hGH transgenic	β-globin	Overexpression in erythroid tissue	Increased bone density and cortical thickness	147
IGF-I transgenic	Human osteocalcin	Overexpression in mature osteoblasts	Increased bone formation rate, trabecular and cortical bone volume	148
IGF-I transgenic	3.6-kb rat collagen 1α1	Overexpression in immature and mature osteoblasts	Increased femur length, cortical width and cross- sectional area; increased calvarial thickness	149
PAPP-A transgenic	2.3-kb rat collagen 1α1	Increased free IGF in bone microenvironment	Increased calvarial thickness and BMD; increased size of long bones	151
Chondrocyte IGF-I KO	3.0-kb mouse collagen 2α1	IGF-I disruption in chondrocytes	Decreased length, bone size, and BMD	52
Osteoblast IGF-I KO	Entire mouse collagen 1α2 gene	IGF-I disruption in cells of osteoblast lineage	Decreased length, bone size, and BMD	53

PAPP-A, An IGFBP-specific protease; hGH, human GH.