title: GSM7680399: AT2 cells (CT26 Distal) rep1; Mus musculus; ATAC-seq
library_construction_protocol: The Omni ATAC-seq protocol was applied with few modifications. Omni ATAC-seq was performed on 50,000 FACS-purified AT2 cells from distal lung or metastatic niche of 4T1 and CT26 lung metastases. Briefly, purified AT2 cells were incubated in 50 μL of cold ATAC-seq resuspension buffer (RSB) for 3 min on ice and then diluted on RSB containing 0.1% Tween-20. Isolated nuclei were resuspended on transposition mix containing the Tn5 transposase (manufactured and assembled in house at a final concentration of 100 nM/reaction) for 30 min on 37 ºC. Transposed fragments were purified and cleaned using the AMPureXP beads (Beckman Coulter, A63881) as per the manufacturer's instructions. The libraries were then pre-amplified, the required number of additional amplification cycles was manually assessed  and amplified again using the NEBNext High-Fidelity 2X PCR Master Mix (Thermo Fisher Scientific, M0541S). Finally, the libraries were purified once again using the AMPureXP beads and submitted for sequencing on NovaSeq 6000 (30 million reads/sample).