Drosophila polytene chromosomes stained with antibodies against a chromatin-remodeling ATPase called Kismet (blue), RNA polymerase II with low CTD phosphorylation (red), and RNA polymerase II with high CTD phosphorylation (green).

[Reproduced with permission of The Company of Biologists, from Srinivasan, S., et al., “The Drosophila trithorax group protein Kismet facilitates an early step in transcriptional elongation by RNA Polymerase II,” Development, 2005, 132(7):1623-1635; permission conveyed through Copyright Clearance Center, Inc.]