Lactate production (μM) in medium of MCF-7 cells growing in 1 nM (black bar), 5 mM (striped), or 25 mM (checkered) glucose after 4, 6, 12, 24, or 48 h of normoxia (A) or hypoxia (B). Lactate concentrations were determined by detection of NAD-linked conversion of lactate to pyruvate by lactate dehydrogenase at 340 nM. Values are mean ± SEM from 3 separate experiments. * denotes a significant (p < 0.05) increase in lactate compared to baseline. Note a 2-fold increase in lactate production with hypoxia and physiological or high glucose compared to normoxia. Normoxia figure was previously published .