Fig. 7. Cbfa-1 is required for NO-induced MMP-13 expression in differentiating MC3T3-E1 cells. MC3T3-E1 cells were differentiated and, on day 7, Cbfa-1 and GAPDH expression were silenced by RNA interference (siRNA). Cbfa-1, MMP-13 and GAPDH expression were evaluated by immunoblot. The capacity of Cbfa-1-silenced cells to produce NO was evaluated by measuring nitrite accumulation from culture supernatants (lower panel: n=3, mean ± s.d., ^*P<0.05 versus day 0).