Cell survival depends on having a plentiful and balanced pool of the four chemical building blocks that make up DNA—the deoxyribonucleosides deoxyadenosine,deoxyguanosine, deoxycytidine, and thymidine,often abbreviated as A, G, and C,and T. However, whether too many of these components pile up, or whether their normal ratio is disrupted,that can be deadly for the cell.
Source: phys.org