For example the SLC-0111 analog labeled with 18F as well as a coumarin derivative incorporating the same isotope, although highly potent as in vitro CA IX inhibitors in vivo, in HT-29 (colorectal) xenografts in mice did not accumulate in the tumor, but were principally present in the blood, liver and nose of the animals, making them inappropriate as PET agents. This evidence concerns the gene CA9 and neoplasm.