SMAD1 and central nervous system cancer: LN18 glioma cells were pretreated with control (siCL), Smad1 (siSmad1)-, or Smad5 (siSmad5)-specific siRNA and then were kept as controls or treated with 80 μM DAPT for 48 or 96 h and then cell migration was examined by chemotaxis (Fig. 5A) and wound-healing (Fig. 5B) methods.