When murine fibrosarcoma L929 cells, a TNF-sensitive cell line, were treated with recombinant human tumor necrosis factor-$alpha$ (rhTNF-$alpha$), the activities of glycolytic regulatory enzymes and lactate dehydrogenase increased up to 100-150% compared to the control L929 cells after TNF treatment. By using various metabolic inhibitors and activators, it was found that cAMP-dependent protein kinase is responsible for the increase of activities of the glycolytic enzymes. The activities of glycolytic regulatory enzymes and lactate dehydrogenase of TNF-resistant A549 cells, a human lung carcinoma cell line, did not increase significantly compared to TNF-sensitive L929 cells upon TNF treatment. In contrast, the pyruvate carboxylase activities of A549 cells, but not L929 cells, increased up to 30~40% after TNF treatment. The data suggest that pyruvate carboxylase activity may contribute to the compensation of energy loss mediated by TNF treatment in TNF-resistant A549 cells.