Figure 2. Coordination of Cell Growth and Nutrient Uptake.

Eukaryotic cells import low molecular weight nutrients such as glucose and amino acids through plasma membrane transporters and can also ingest bulk extracellular macromolecules through the non-selective endocytic pathway of macropinocytosis. a, Unicellular eukaryotes take up nutrients as they become available in the environment. In addition to supplying bioenergetic and biosynthetic pathways, nutrients function as direct signals for unicellular organisms to commit to growth and proliferation. b, The cells of metazoan organisms have lost the ability to regulate nutrient acquisition cell-autonomously; rather, they are instructed by growth factor signalling pathways to engage in nutrient uptake, thereby ensuring that nutrient supply matches the metabolic demands of cell growth. c, Components of growth factor signalling pathways are frequently mutated in cancer. These oncogenes cause cellular transformation in part by granting a cell autonomy over nutrient uptake and by increasing availability of precursors for macromolecular synthesis.