Fig. 6. Retroviral expression of Barx2 in limb bud micromass cultures increases Col2a1 gene expression. (A) Barx2-retrovirus infection induced approximately fivefold increase in Col2a1 mRNA relative to control infections as measured by real time PCR. n, number of experiments. (B) Expression of HD-BBR-C construct increases collagen II protein expression in micromass cultures.