On the contrary, inhibition of the replication stress sensing kinase ataxia telangiectasia and Rad3-related protein (ATR) in leukemia cells down-regulates the activity of RNR and deoxycytidine kinase (dCK), rate-limiting enzymes of respectively the de novo and salvage dNTP synthesis pathways [57]. The gene discussed is NR2E3; the disease is leukemia.