Fig. 9. Overexpression of constitutively active Stat3 (Stat3C) in chondrocytes promotes precocious proliferation in vivo and rescues growth plate defects in gp130 deletion mutants.

Induction of Stat3C expression at P2/P3 resulted in significant increases in chondrocyte number in both growth plate (a) and articular cartilage (b) in Acan-Cre^+/ERT2;Rosa26-Stat3C^fl/+ mice as compared to Rosa26-Stat3C^fl/+ control animals at 1 month. c EdU was injected intraperitoneally 4 h before harvesting knee joints at 1 month of age. EdU⁺ cells in proximal tibial growth plate chondrocytes were scored. POC primary ossification center, SOC secondary ossification center. Boxed areas delineate the growth plate. d Induction of constitutively active Stat3 in Acan-Cre^+/ERT2;gp130^fl/fl mice resulted in significantly thicker growth plates at 1 month of age. In all panels, scale bars = 50 µm; n = 4–6 for each group.