RIF‐1, LNM35 (human pulmonary carcinoma cell line), PC9, A549 (human lung adenocarcinoma cell line) cells.401, 402 RIF‐1, 38C13 (mouse B‐lymphoma cell line), HCT116 (human colon carcinoma cell line), MDA‐MB‐231 (human breast adenocarcinoma cell line), PC9 tumors.401, 402, 403, 404 Probe detects activated caspases. For proper analysis of PET data in tumors with necrotic centers, voxel‐wise data analysis is a must. Here, RIF1 is linked to lung adenocarcinoma.