The lung-into-liver swap abrogated SMAD4’s tumor-suppressive response in the liver, while the liver-into-lung swap impaired SMAD4’s tumor-promoting response in the lung, which was reflected in the unchanged tumor burden and fractions of Ki67+ and p57+ cells upon Smad4 restoration in both organs (Fig. 5c–h). Here, SMAD4 is linked to neoplasm.