FIG. 1.

Ectopic overexpression of Smurf2 under Col2a1 promoter promotes endochondral ossification. (A and A′) Phenotype of knee joints from 7.5-mo-old wildtype (A) and Col2a1-Smurf2 (A′) mice. Arrows and arrowheads indicate cartilage degeneration and osteophytes, respectively. (B and B′) Immunofluorescence of wildtype (B) and Col2a1-Smurf2 (B′) tibias at 16.5 dpc. Arrows indicate overexpression of Smurf2 in the perichondrial cells. (C–I′) Skeletal preparation of mouse embryos. Wildtype (C and G) and Col2a1-Smurf2 (C′ and G′) embryos were stained with Alcian blue and alizarin red at 14.5 (C and C′) and 16.5 dpc (G and G′). Forelimbs (D, D′, H, and H′), hindlimbs (E, E′, I, and I′), and rib cages (F and F′) were separated from C, C′, G, and G′ with the aid of a dissecting microscope. Black arrows indicate the hypertrophic region; red arrows indicate the ossification region. S, scapula; H, humerus; R, radius; U, ulna; FE, femur; T, tibia; FI, fibula. Green line indicates the length of ossification domain.