Thymidine 3',5'-diphosphate (Deoxythymidine 3′,5′-diphosphate) tetrasodium is a selective inhibitor of staphylococcal nuclease and tudor domain containing 1 ( SND1 , the MicroRNA regulatory complex RISC subunit) and [3,5- 2 H 2 ] tyrosyl nuclease. Thymidine 3',5'-diphosphate tetrasodium has anti-tumor activity and can also be used as a catalyst in biochemical reactions.