Fig. 5. Alteration of osteoblast specific gene expression and increased mineralization by the Axin2 deletion. Primary calvarial osteoblast precursors isolated from nasal/frontal bones of the Axin2^+/+ and Axin2^–/– littermates were cultured in differentiation media for up to 9 days. Quantitative real time RT-PCR analyses were performed to examine expression of osteopontin and osteocalcin. The graphs represent the expression levels (in arbitrary units) of osteopontin (A) and osteocalcin (B) during the course of osteoblast differentiation. Primary calvarial osteoblasts from nasal/frontal bones of the Axin2^+/+ (C) and Axin2^–/– (D) littermates were maintained in differentiation media for 3 weeks. Von Kossa staining analyses show increased mineralization in Axin2^–/– osteoblast cultures compared with wild-type cultures (C,D). Scale bars: 0.1 mm in C,D.