Fig. 7. Bone nodule formation by Icap-1^−/− calvarial osteoblast is defective.

(A) Primary Icap-1^+/+ and Icap-1-deficient osteoblasts were cultured for 4 weeks in inductive medium and stained with alizarin red for monitoring bone nodule formation. Icap-1^−/− cultures show fewer and smaller mineralized nodules (arrows) compared with wild-type cultures (Icap-1^+/+). The result is representative of at least 3 independent experiments from 3 different animals. Bar, 1 mm. (B) Immortalised osteoblasts SV2.1 Icap-1^−/−, SV6.5 Icap-1^+/+ or SV2.1-Icap-1^resc were cultured in inductive medium for 3 weeks and mineralized nodules were identified by alizarin red staining. Icap-1^−/− osteoblasts show a significantly reduced nodule formation compared to wild-type or Icap-1^resc osteoblasts. The means and S.D. were calculated from 3 independent experiments (*, P<0.05, **, P<0.0001)