One to two million cells were then fixed with 4% PFA for 10 minutes and neutralized with glycine. The cells were stained with a rabbit anti-lamin B1 antibody (Abcam, ab16048) and the tyramide signal amplification (TSA) reaction was done with the Biotin-XX-Tyramide kit (Invitrogen, #B40921). The reaction was verified by staining a fraction of the cells with Streptavidin-488. Labeled cells were lysed with RIPA buffer containing PMSF and then sonicated on Bioruptor Pico. A 1/10th volume input sample was taken, and the remainder of the lysate was used for Streptavidin pulldown using Pierce Streptavidin conjugated magnetic beads (Thermo, #88816). DNA was extracted using Ampure XP beads. Libraries were prepared with the Takara ThruPLEX DNA-seq kit (Takara, #R400674).