FAP and fibrosarcoma: Although [125I]I-FAPI-01 exhibited rapid internalization in both murine FAP-transfected human embryonic kidney (HEK) cells and human FAP-transfected fibrosarcoma HT-1080 cells in vitro, time-dependent efflux and enzymatic deiodination of [125I]I-FAPI-01 eliminated its further preclinical evaluation.