Insulin Dependence of Cells in Primary Culture: Influence on Ribosome Integrity

WE have found that, unlike cells in continuous culture (for example, L cells and HeLa cells), primary cultures of chick embryo fibroblasts have a demonstrable requirement for insulin. The requirement is manifest when insulin is added to the culture medium in the effect on protein synthesis by cells and on the capacity of ribosomes prepared from such cells to synthesize protein in vitro .