Figure 1. Metabolic profiling reveals extensive changes in metabolite levels during the cell cycle. HeLa cells were synchronized by 2TB and the metabolite levels, at different time points after the release, were obtained by GC/MS or LC/MS and normalized to total protein content. The levels of the metabolites at different phases of the cell cycle were deconvoluted using FACS data as described under “Materials and Methods”. (A) Distribution of the cyclic metabolites in biochemical classes and (B) relative levels of the lysophosphatidylcholine (LysoPC) and lysophosphatidylethanolamine (LysoPE) species. (C) Schematic model of PC/PE metabolism. FA, fatty acids; PC, phosphatidylcholine; PE, phosphatidylethanolamine; GPC, glycerophosphorylcholine; GPE, glycerophosphoethanolamine.