The MYC oncogene encodes a master transcription factor, Myc, which regulates genes involved in ribosome biogenesis, lipid synthesis, nucleic acid synthesis, intermediary metabolism, and cell growth and proliferation. The genomics of Myc target genes has been well-established through global mapping of Myc binding sites in a variety of different cancer cell lines. These studies highlight the importance of Myc in regulating glucose and glutamine metabolism as well as mitochondrial and ribosomal biogenesis. These genomic studies, however, only become relevant with the companion metabolic studies using a variety of methods to measure oxygen consumption, glucose uptake, or metabolic pathways based on (13)C-labeled glucose or glutamine uptake. These methods are described herein.