In contrast, capecitabine is first converted in the liver to 5’-deoxy-5-fluorouridine (doxifluridine; DFUR), which then forms 5FU upon entry into cells via a TP-catalyzed reaction (Fig. 1), which appears to be more active in cancer cells than in normal cells, possibly leading to selective accumulation of 5FU in tumors (Longley et al. 2003). The gene discussed is TYMP; the disease is cancer.