Sensitivity analysis to measured fluxes and to parameters. The sensitivity represented in the heat map (A) was computed for the compartmented network of CHO-K1 when [U-13C6] glucose was used as a labeled substrate, , where is the sensitivity of the estimated flux v
, re-estimated using values of the measured flux v
at the border of the confidence interval. v
* is the average measured flux. The bar chart below (B) shows the normalized sensitivity of the objective function (SensSSQD) to the free parameters (fluxes and rev = reversibilities). The sensitivity was obtained as a mean value of 100 perturbations of each parameter around the estimated value: , where SSQD* is the optimized value of the objective function (eq. 6), and p
* is the estimated value of parameter i. The rates v
correspond to the rates in the network shown in Figure 1A. Abbreviations: subscripts: c: cytosolic, ex: extracellular, m: mitochondrial; ALA: alanine; AcoA: acetyl coenzyme A; AKG: alpha-ketoglutarate; ASN: asparagine; ASP: aspartate; CIT: citrate; G6P: glucose 6-phosphate; GLC: glucose; GLN: glutamine; GLU: glutamate; GLY: glycine; LAC: lactate; MAL: malate; OAA: oxaloacetate; PEP: phosphoenolpyruvate; PG: phosphoglycerate; PYR: pyruvate; SER: serine.