Figure 6. Antitumor activity of melatonin plus DDP in vivo in a lung metastasis model. (A) Tumor progression timeline with experimental treatment time points. (B) Tumor cell luminescence from each mouse in each group was acquired on treatment day 28. (C, D) Representative front images (C) and back images (D) of macroscopic lung metastases, arrowheads indicate the metastatic nodes. (E) Quantification of the average number of macroscopic metastatic nodes formed on the lung surface. (F) Paraffin-embedded tumor sections were stained with H&E, anti-Ki67, and β-catenin antibodies (Scar bar: 100 μm). Right panel: quantification of the proliferation index and β-catenin index in tumor sections. These animal experiments were repeated once (n = 3 mice per treatment group). Data presented are the mean ± SD; **P < 0.01 compared with control using Student t-test.