Nature 388, 598–602 (1997)

The meaning of the sentence that describes Fig. 5 of this Letter was distorted by erroneous duplication of text and should read: “Comparison of the ATPase activities of CHRAC with that of purified Drosophila topoisomerase II (Fig. 5) showed that topoisomerase II was only stimulated by free DNA, whereas CHRAC was stimulated by free DNA as well as by nucleosomes.”