Pteridine derivative that is abundant in liver and green plants and is a growth factor for some bacteria. The biochemically active form is tetrahydrofolate. A form of vitamin B obtained from green leafy vegetables, e.g. spinach. It is essential for synthesis of DNA and therefore the growth and division of cells.
It was apparent, even from these early studies with both folic acid antagonists and glucocorticoids, that childhood acute leukemias were among the most responsive of all cancers studied.