after shift of mutant cells to the nonpermissive temperature , thymidine kinase activity decreased , and minimal levels ( i.e. , less than 3 % of those observed for 'wild-type ' k 21 cells at the respective temperature ) were attained within 16 h in heat-sensitive and after 3-4 days in cold-sensitive mutants , which is in good agreement with kinetics of accumulation of heat-sensitive and cold-sensitive cells in g1 phase .
C0007634
cells
C0079395
g1 phase