Figure 6. Model showing the coordinated changes in lipid metabolism that support membrane synthesis from G₂/M to G₁ phase of the cell cycle. De novo FA synthesis increases from G₂/M to G₁ to support de novo phosphatidylcholine synthesis. During this time, the reacylation rate of LysoPC surpasses PC deacylation, thus contributing to membrane accumulation (thick arrows). A reduction in AMPK-mediated inhibition of de novo FA synthesis (dashed line) may coordinately regulate membrane synthesis and mitosis progression. An impaired membrane synthesis arrests the cells at G₂/M, probably before ana/telophase, suggesting the presence of a “lipogenic checkpoint.” For simplicity the lipid metabolism from G₁ to S and from S to G₂/M are not depicted (gray). FA, fatty acid; LysoPC, lysophosphatidylcholine; P-Chol, phosphocholine; CDP-Chol, CDP-choline; DAG, diacylglycerol; PC, phosphatidylcholine.