Figure 7.

Glycolytic activity in different glucose/glutamine conditions as represented by pyruvate kinase activity and [U-¹³C₆]glucose-derived metabolite flux to ¹³C-pyruvate and ¹³C-lactate as well as ¹³C-alanine in MCF-7 and MDA-MB-231 cells. (A,B) PK activity was determined in lysates from monolayer cultures of MCF-7 and MDA-MB-231 cells after 72 h in the indicated glucose/glutamine conditions. The enrichment of ¹³C-pyruvate (C,D), ¹³C-lactate (E,G), and ¹³C-alanine (F,H) was determined following a 2 h incubation with the indicated ¹³C₆-glucose/glutamine concentrations of cells after their 72 h incubation in unlabeled glucose/glutamine conditions. Shown are averages with the s.e.m. from two independent experiments for each condition. For MCF-7 cells, the raw data from [39] were used.