The fibroblast activation protein (FAP) is a known biomarker expressed on the surface of cancer-associated fibroblasts (CAF), as well as an important target that distinguishes normal fibroblasts from CAF. Researchers from National Yang-Ming University recently reported the discovery and preclinical evaluation of a novel PET tracer, [18F]FEQGP, being developed for the detection of FAB expression in CAF imaging.