Smad5 regulates p75NTR expression in BMP7-stimulated human LN18 glioblastoma cells. (A) Human LN18 glioblastoma cells were kept as the controls or treated with BMP7 (50 ng/mL) for 1, 4, 8, and 24 h and then the Smad1/5 phosphorylation was determined by Western blot. (B) Human LN18 glioblastoma cells were transfected with control-, Smad1- or Smad5-specific siRNA, kept as the controls or treated with BMP7 (50 ng/mL) for 24 h and then the p75NTR protein expressions were determined by Western blot. Results in (A,B) are representative of three independent experiments with similar results. Statistic data in (A,B) are mean ± SEM from three independent experiments. (A) *, p < 0.05 vs. CL group. (B) *, p < 0.05 vs. siCL-CL group; #, p < 0.05 vs. siSmad5-CL group.