in an extension of these experiments , cells in a quiescent state ( go cells ) were stimulated by the 'serum-step-up ' method of burk ( 1970 ) to grow and to enter a synchronous wave of dna synthesis ( s-phase cells ) , 87 % of the cells synthesizing dna at 20 h after the 'serum-step-up ' .
C0080129
s-phase
C0007634
cells