Fig. 1. Compromised JunB expression in mutant mice leads to growth retardation and shortening of long bones. (A) Comparison of an 8-week-old control (311K; bottom) and a junB^–/– Ubi-junB (311R; top) mouse, (B) reduced length of tibiae and femurs of age matched female junB^–/– Ubi-junB (311R; open circles) compared to control mice (filled circles). Black bars indicate the mean values of control (n=10, wt and 311K) and mutant animals (n=7), (C) RT-PCR analysis of junB mRNA with total RNA derived from long bone epiphysis of 8-week-old junB^–/– Ubi-junB mice (311R) and control (311K) littermates. RT-PCR analysis for ß-Tubulin served as a control for quality and quantity of the cDNA samples. (D) Expression of JunB protein was detected by immunohistochemistry in proliferative (PC) and prehypertrophic chondrocytes, but not in hypertrophic chondrocytes (HC), on 6 µm growth plate sections from 4-week-old control (311K) mice. Additionally, expression of JunB protein was demonstrated in control osteoblasts and osteocytes in the trabecular bone area (arrows). In junB^–/– Ubi-junB bone sections only very few chondrocytes, but no osteoblasts, were positive for JunB protein (arrows). Control sections were incubated only with the second antibody (left panel). Sections were counterstained with Haematoxylin; magnification was 20x.

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