Phenylacetate inhibits cancer cell proliferation by reducing Gln availability in the blood [86], while Bis-2-5-phenylacetamido-1,3,4-thiadiazol-2-ylethyl sulfide (BPTES), an inhibitor of the glutaminase—the rate-limiting step in Gln catabolism—blocked the growth of xenografts [29]. The gene discussed is GLS; the disease is cancer.