We found that RRM2B is associated with the flux of 3-ureidopropionate, a product of the uracil degradation pathway, which is secreted by all ccRCC cell lines (range: 0.016 to 0.102 fmol cell−1 h−1) (Fig. 6C, left). The gene discussed is RRM2B; the disease is nonpapillary renal cell carcinoma.