Deoxycytidine Kinase, a DNA salvage pathway enzyme, is a responsible for converting deoxycytidine into deoxycytosine monophosphate expending an ATP. It is also promiscuous phosphorylator of other nucleosides and can use other nucleotides. Its promiscuity is often the target of drugs precisely because of its promiscuity. It can be exploited to activate drugs through phosphorylation.