NOTCH1 and neoplasm: However, the tumors in Notch1 siRNA, Notch2 plasmid and combined Notch1 siRNA and Notch2 plasmid treated groups still maintained the slower growth rate and had been shown significant difference of tumor volume in the last half of observation period (p<0.01), but there were no superimposed effect in combination of Notch1 siRNA and Notch2 plasmid treated group.