PGP and neoplasm: [11C]Methionine, an amino acid PET tracer used in tumor detection, has some properties similar to those of [18F]fluciclovine: (1) [11C]methionine is transported via AATs [10]; (2) [11C]methionine accumulates readily in the liver, moderately in the kidney, but accumulates little in the brain [29]; and (3) [11C]methionine accumulation is not affected by P-gp expression [30].