Ribonucleotide reductase requires subunit switching in hypoxia to maintain DNA replication. by Foskolou, IP, Jorgensen, C, Leszczynska, KB, Olcina, MM, Tarhonskaya, H, Haisma, B, D'Angiolella, V, Myers, WK, Domene, C, Flashman, E, Hammond, EM