Chondrocyte hypertrophy is the terminal step in chondrocyte differentiation and is crucial for
endochondral bone formation. How signaling pathways regulate chondrocyte hypertrophic
differentiation remains incompletely understood. In this study, using a Tbx18: Cre (Tbx18
Cre/+) gene-deletion approach, we selectively deleted the gene for the signaling protein
SMAD family member 4 (Smad4 f/f) in the limbs of mice. We found that the Smad4-deficient
mice develop a prominent shortened limb, with decreased expression of chondrocyte …