COL2A1 and fetal growth restriction: In the present study, the protein expression of IGF-1, AKT1/2, SOX9 and Col2a1 in adult IUGR offspring with PEE remained lower in articular cartilage before and after strenuous running, indicating that the local IGF-1 signaling pathway in articular cartilage was low-functioning, consistent with the changes that occurred during the fetal period.