murine erythroleukemia cells were induced to undergo erythroid differentiation by growing in presence of dimethylsulfoxide , butyric acid or actinomycin d. topological linking numbers in closed loops of nuclear dna were measured by means of centrifugation of nucleoids containing superhelical dna in sucrose gradients containing varying concentrations of ethidium bromide .
C0007634
cells
C0007589
differentiation