two heat-sensitive ( reversibly arrested in g1 phase at 39.5 degrees c , multiplying at 33 degrees c ) and two cold-sensitive ( reversibly arrested in g1 phase at 33 degrees c , multiplying at 39.5 degrees c ) cell-cycle mutants of the p-815-x2 murine mastocytoma line were tested for ribonucleotide reductase activity , using cells made permeable to nucleotides .
C0079395
g1
C0007634
cells