In addition, U-13C glutamine tracing revealed that the FTO inhibitor FB23-2 inhibited reductive carboxylation in ccRCC cells with reduced fraction of the reductive metabolites m + 3 aspartate, malate, and fumarate and reduced m + 3/m + 4 aspartate, malate, and fumarate ratios (Fig. 1, D and E, and fig. The gene discussed is FTO; the disease is nonpapillary renal cell carcinoma.