To verify whether large xenografts would respond to SP5-2-LD treatment, mice bearing large lung cancer xenografts (500 mm 3 ) were assigned to three treatment groups. After a course of doxorubicin treatment with a total dosage of 16 mg/kg (2 mg/kg twice a week for eight injections), the tumor sizes in the control PBS and LD groups gradually increased to 3.3 and 2.1 times the tumor size in the SP5-2-LD group (P,0.01) (Fig. 3B) . These results revealed that SP5-2-LD also increased the therapeutic efficacy of doxorubicin in SCID mice bearing large lung cancer xenografts.