Fig. 5. In vitro differentiation of bone marrow-derived stromal cells. (A) In vitro differentiated control (left panel) and junB^–/– Ubi-junB cultures (right panel) derived from marrow stromal cells were stained for ALP activity to measure osteoblast differentiation, or with alizarin Red for osteoblast function. Stromal cells from transgenic mutant lines 311R (right panel) and 288R (data not shown) revealed similar defects in the process of in vitro differentiation. (B) Colony forming unit assay with bone marrow cells from control and junB^–/– Ubi-junB littermates. Colonies were stained for ALP activity and counterstained with Haematoxylin. Representative images are shown on the right. Relative number of colonies (each containing a minimum of 20 cells) was calculated after the total number of control colonies was set to 100%. Bars represent mean ± s.e.m. calculated from two independent experiments done in triplicates.