After the cell division has been completed, the salvage enzymes, no longer required, are degraded. During interphase the cell derives its requirement of nucleoside-5'-phosphates by de novo synthesis, that leads directly to the 5'-monophosphate nucleotides.
Following cell division, the enzymes that break down old cellular components are no longer needed and are degraded. During interphase, cells produce their own nucleoside-5'-phosphates, which then form the building blocks for 5'-monophosphate nucleotides.