Serum-dependent depression of alkaline phosphatase in HeLa cells

Reduction in alkaline phosphatase activity was observed when HeLa S3 cells were grown in Puck's medium containing high concentrations of human serum. This effect was not seen with the enzyme of Chang liver 8A cells. The induction of increased alkaline phosphatase in HeLa S3 by prednisolone or by osmolality changes was not prevented by serum. The concentration of serum in the culture medium had no influence on acid phosphatase activity.