Cell density-dependent changes of glycolipid concentrations in fibroblasts, and loss of this response in virus-transformed cells.

The glycolipids of normal fibroblasts cells at different stages of growth and with differing degrees of susceptibility to contact inhibition have been analyzed, as well as the glycolipids of virally transformed cells. The concentrations (per mg protein) of certain glycolipids, including galactosylgalactosyl-glucosyl-, N-acetylneuraminosylgalactosylglucosyl-, and N-acetylneuraminosyl-(N-acetylneuraminosyl)galactosylglucosyl-c eramide, increase on cell-to-cell contact of susceptible cells. The concentrations of these glycolipids decrease when susceptibility to contact inhibition is lost as a result of extensive passage in vitro or transformation by simian virus 40 or polyoma virus, and in all the malignant cells examined, the concentrations of these glycolipids were independent of cell density.