The glucose analogue 2-deoxy-D-glucose (2-DG) restrains growth of normal and malignant cells, prolongs the lifespan of C. elegans, and is widely used as a glycolytic inhibitor to study metabolic activity with regard to cancer, neurodegeneration, calorie restriction, and aging. Here, we report that separating glycolysis and the pentose phosphate pathway highly increases cellular tolerance to 2-DG. This finding indicates that 2-DG does not block cell growth solely by preventing glucose catabolism. In addition, 2-DG provoked similar concentration changes of sugar-phosphate intermediates in wild-type and 2-DG-resistant yeast strains and in human primary fibroblasts. Finally, a genome-wide analysis revealed 19 2-DG-resistant yeast knockouts of genes implicated in carbohydrate metabolism and mitochondrial homeostasis, as well as ribosome biogenesis, mRNA decay, transcriptional regulation, and cell cycle. Thus, processes beyond the metabolic block are essential for the biological properties of 2-DG.cell growth inhibition ͉ glycolysis ͉ off-target effect ͉ pentose phosphate pathway ͉ carbohydrate metabolism 2 -Deoxy-D-glucose (2-DG) is a stable glucose analogue that is actively taken up by the hexose transporters and phosphor ylated but cannot be fully metabolized. 2-DG-6-phosphate accumulates in the cell and interferes with carbohydrate metabolism by inhibiting glycolytic enzymes. 2-DG-6-phosphate inhibits phosphoglucose isomerase (PGI) in a competitive, and hexokinase (HXK) in a noncompetitive, manner (1-3). On the cellular level, 2-DG provokes rapid growth inhibition and results in altered glycosylation that is highly dependent on catabolic glucose intermediates (4, 5).2-DG has been used in numerous studies focused on the effects of reduced metabolic rates. Recently, 2-DG has been used in this study of glycolytic inhibition with respect to calorie restriction and aging. 2-DG increases the lifespan of C. elegans, an effect that is reversed by antioxidants (6, 7). Moreover, 2-DG mitigates disease progression in a murine model of temporal lobe epilepsy (8), possibly due to the repression of the BDNF promoter. 2-DG shows possibilities as an antiviral drug, as it targets gene expression in papillomavirus (9). Finally, 2-DG has been thoroughly studied in regard to cancer biology. Malignant cells exhibit increased glucose metabolism compared with surrounding tissue (10) and, therefore, increased 2-DG uptake. 2-DG efficiently inhibits tumor progression and is a focus of clinical trials (reviewed in ref. 11).In general, it is assumed that the biological effects of 2-DG are the consequence of a block in carbohydrate catalysis, implying that 2-DG treated cells, unable to metabolize glucose, stop growing as a result of a lack of energy and metabolic intermediates. However, several observations bring this assumption into question. First, only a moderate decline in ATP has been observed in 2-DG-treated eukaryotes (7,12). Second, a current study reveals that tumor cells react differently to 2-DG than to its close analogue 2-fluorod...