FAP and neoplasm: In tumors, FAP expression is detected using near-infrared (NIR) fluorescent probes and quinoline-based FAP-targeted radiotracers (68Ga/18F-labeled FAP inhibitor [FAPIs]), which have shown intense tumor uptake and favorable image contrast capabilities in various tumors (Li et al.2012; Lindner et al.2018; Xing et al.2018).