Non-compratmented (A) and compartmented (B) networks of the CHO-K1 central metabolism used for simulations. Irreversibility is indicated by simple arrows, and reversibility by double arrows. The reactions depicted in 1B are listed in detail in the Additional file 1 together with fluxes and reversibilities determined. Subscripts meaning: ex – extracellular; c – cytosolic; m – mitochondrial. Abbreviations: AA –amino acids; AcoA – acetyl CoA; AKG – alpha-ketoglutarate; ALA – alanine; ASN – asparagine; ASP – aspartate; CIT/ICI – citrate/isocitrate; G6P – glucose 6-phosphate; GLC – glucose; GLN – glutamine; GLU – glutamate; GLY – glycine; MAL – malate; OAA – oxaloacetate; PEP – phosphoenolpyruvate; PG – phosphoglycerate; PYR – pyruvate; SER – serine.