Four weeks of IGF-1 treatment results in increased serum levels of IGF-1 and IGFBP-3 and an increase in body and femoral lengths. (a) Serum levels of IGF-1 following 4 weeks of IGF-1 injections were determined by RIA as described above. (b) Serum levels of IGFBP-3 were determined by ligand blot assay. The graph shows quantification of 125I–IGF-1 binding to IGFBP-3 in samples from control, LID, ALSKO, and LID+ALSKO mice (n = 8 per group). (c) Body length of control, LID, ALSKO, and LID+ALSKO mice at 8 weeks of age, with and without IGF-1 treatment. (d) Length of femurs of ALSKO and LID+ALSKO mice at 8 weeks of age, with and without IGF-1 treatment.