To test this hypothesis, Rb1−/−, p53−/−, and p130−/− (RPP) murine SCLC cells stably expressing either a control vector or IFITM3 (Supplementary Fig. 5A) were subcutaneously transplanted into immunocompetent C57BL/6 mice. Here, IFITM3 is linked to small cell lung carcinoma.