TSPO and neoplasm: Previous TSPO-PET imaging studies predominantly investigated the GL261 model using [18F]DPA-714 (2), [18F]PBR111 (21), and [18F]GE-180 (9) TSPO-PET, successfully showing the possibility to monitor TSPO expression and tumor growth in vivo. The main finding of our investigation was high TSPO-PET values of SB28 lesions, which were distinctly elevated over sham lesions already at week-1 and remained at a high level until week-3.