ATAC‑seq was performed as described earlier (Buenrostro et al., 2013; Buenrostro et al., 2015) with some modification for Drosophila cells. In brief, 50,000 S2 or Kc cells, also with prior RNAi, were used per reaction. Cells were washed in 100 µL PBS, resuspended in 100 µL Lysis Buffer (10 mM Tris/HCl pH 7.4, 10 mM NaCl, 3 mM MgCl2, 0.1% (v/v) IGEPAL CA‑630) with cOmplete, EDTA‑free Protease Inhibitor Cocktail (Sigma‑Aldrich) and incubated for 3 min on ice. Nuclei were spun down at 4°C for 10 min at 600 g, resuspended in 50 µL 1x TD buffer with 2.5 µL TD Enzyme (Illumina) and incubated with slight agitation for 30 min at 37°C. Tagmented DNA was purified with MinElute kit (QIAGEN). Cycle number for library amplification was determined by qPCR. Cycle number at quarter maximal intensity was used for library amplification (typically 11‑13 cycles). ATAC libraries were purified with MinElute kit (QIAGEN).