Figure 19-24 A model for chromosome compaction during mitosis. (a) The folding of chromosomes into consecutive loops leads to the formation of proteinaceous fibers at loop bases. (b) These chromosome axes are then further compressed to generate highly condensed chromosomes. The proteins responsible for loop formation are likely to be condensins.

[Republished with permission of AAAS, from Science, N. Naumova et al., 342, 6161, 2013; permission is conveyed through Copyright Clearance Center, Inc.]