addition of mgcl ( 2 ) to the medium , to increase the concentration of mg ( 2+ ) ions by 15mm , 30min before addition of serum , had no effect on the stimulation of cell growth , but inhibited the accumulation of cellular spermidine , so that the spermidine/spermine molar ratio was lower in these cultures than in cultures that had received no additional cations .
C0022023
ions
C0007447
cations