Ribonucleotide reductases (RNRs) catalyse the conversion of nucleotides to their corresponding deoxynucleotides in every living cell.[1] Due to their central role in DNA replication and repair, they have been a target for cancer therapeutics.[2]E. coli class Ia RNR, a paradigm for class Ia enzymes including human RNR, consists of two homodimeric subunits, α2 and β2. The gene discussed is NR2E3; the disease is cancer.