Evaluation of sternum in 10-week–old JNK1/2 dKO and control (CTRL) mice. A and B: Alcian blue/Alizarin red staining showing the presence of a cartilaginous tissue (blue stain, yellow circles) between sternebrae in the JNK1/2 dKO mice. Boxed areas in left panels of A and B are shown in higher-magnification in right panels. B–D: Safranin O/fast green staining showing a tissue rich in proteoglycans between sternebrae (C and D) and the expansion of this cartilaginous tissue in the dKO (B). n = 4 (A and C, CTRL/Het); n = 5 (B and D, dKO). Scale bars: 5 mm (A and B, left panels); 2.5 mm (A and B, right panels); 20 μm (C and D). GP, growth plate; Het, heterozygous.