NLN and NEW inhibit tumor metastasis to the lung in MDA-MB231 experimental breast tumor metastasis model. (A) Treatment protocols. MDA-MB231-luc cells were injected intravenously into BALB/c nude mice. At 1 h post-injection, the mice received intravenously injected NLN, NEW, or control peptide (14.2 mg/kg body weight, black arrows, thrice weekly for 3 weeks) and orally administered crizotinib (25 mg/kg body weight, red arrows, twice weekly for 3 weeks). (B) In vivo whole-body luminescence imaging and monitoring of metastatic tumor growth in the lungs of mice treated with either NLN or NEW and crizotinib alone or in combination. (C) Quantification of the total photon flux (number of photons/second) in the whole body. (D) Number of metastatic tumor nodules in the lungs. (E) Lung weights. (F) Survival rates. (G) Body weights. Data are shown as the means ± S.E. (n = 10/group). *, P < 0.05; **, P < 0.01; ***, P < 0.001 compared with control peptide by one-way ANOVA. Ctrl, control peptide.