Smad7 ablation compromises cell proliferation via the enhanced
canonical transforming growth factor–β (TGF-β) signaling. (A,
B) Western blot analyses show the levels of p21, cyclin D1, and
p-Smad2/3 in control and Smad7−/− tooth germ cells
harvested at E15.5 (A) and at P0 (B) after 5 d in cell culture in the presence or
absence of SB431542. (A′, B′) Quantitative reverse
transcription polymerase chain reaction analyses of Cdkn1a and
Ccnd1 expression in control and
Smad7−/− tooth germ cells harvested at E15.5 (A′) and at
P0 (B′) after 5 d in cell culture in the presence or absence of SB431542.
(A′′, B′′) Growth curves, plotted from CCK8 assays, of
control and Smad7−/− tooth germ cells harvested at E15.5
(A′′) and at P0 (B′′) in the presence or absence of SB431542. Statistical analysis was
performed using Student’s t test. *P < 0.05.
**P < 0.01. ***P < 0.001.