normal and rous sarcoma virus-infected chicken fibroblasts proliferate maximally in a culture medium containing a physiological ( 10 ng/ml ) concentration of 5-methyltetrahydrofolic acid or folinic acid ( 5-formyltetrahydrofolic acid ) , while their maximal proliferation requires a hyperphysiological ( 1000 ng/ml ) concentration of folic acid .
C0023413
5-formyltetrahydrofolic acid
C0016410
folic acid