Folinic acid calcium salt (also known as leucovorin calcium) is a vitamin derivative used in a variety of laboratory applications. This 1g quantity is widely utilized in nucleic acid research and for enhancing the effects of antifolate drugs in cancer treatment. Leucovorin is often used as a rescue therapy to counteract the toxic effects of certain chemotherapy drugs, particularly methotrexate. It can also be used to reverse the effects of folic acid antagonists. Additionally, leucovorin plays a role in enhancing the efficacy of drugs like fluorouracil (5-FU) in cancer treatments. It is commonly used in research involving cellular metabolism, folate biochemistry, and chemotherapeutic drug development.