Stimulation of glucose transport in cultures of density-inhibited chick embryo cells.

The rate of glucose transport in sparse, rapidly growing chick-embryo fibroblasts is much greater than that in density-inhibited cells. The addition of fresh chicken serum or trypsin to the medium of density-inhibited cells causes a large increase in the rate of glucose transport that is detectable 15 min after addition. The increase in glucose transport precedes the increase in DNA synthesis by 5-6 hr. Only small changes in rates of transport are seen with nucleosides or a nonmetabolizable amino acid. The increase in glucose transport requires protein synthesis but not RNA or DNA synthesis.