The serum dependence of the occurrence of N-glycolylneuraminic acid in HeLa cells

The occurrence of N-glycolylneuraminic acid in HeLa cells is shown to be due to the calf serum added to the growth medium, and not to their cancerous nature. When Hela cells are grown with human serum as supplement, only N-acetylneuraminic acid can be found. The ganglioside composition of these cells is also reported.