At least two to tango: Choreographing chromatin through cooperative footprints.

Two recent papers, Rao et al. (2021), in this issue, and Sonmezer et al. (2021), investigate transcription factor cooperativity at cis-regulatory elements. Using data from nuclease- and methyltransferase-footprinting experiments, they demonstrate that factor co-occupancy at regulatory elements commonly occurs in vivo and is conserved from fly to mouse.