Figure 4.

Involvement of Smad3 in TGFβ1-induced growth inhibition. (a) Mitigation of TGFβ1-induced, but not high Ca²⁺-induced, growth inhibition of NHK cells by down-regulation of Smad3. The cells were treated with 0.2 μM of siRNA and PEI-conjugated anti-S100C/A11 antibody 48 h and 1 h before, respectively, to the exposure to 1 ng/ml of TGFβ1 or 1.5 mM Ca²⁺. Ct, control; GA, siRNA against GAPDH; Sm3, siRNA against Smad3; Ab, PEI-conjugated anti-S100C/A11 antibody. Standard error among three wells. (b) NHK cells were treated with various agents under conditions similar to those in panel a and analyzed by Western blotting. SC, antibody against S100C/A11. For other abbreviations, see panel a. (c–e) After treating NHK cells with the various agents under conditions similar to those in panel a, cell lysates (150 μg of protein) were immunoprecipitated with respective antibodies and the precipitates and supernatants that were condensed using acetone were simultaneously analyzed. C, control; TGF, TGFβ1 1 ng/ml; Ca, Ca²⁺ 1.5 mM.