AT2 cells (2 × 107) were isolated from 10- to 12-wk-old C57BL/6 mice. Active Motif Epigenetic Services performed ChIP assays. Cells fixed with 1% formaldehyde for 11 min were quenched with 0.25 M glycine and then were swollen in lysis buffer for 30 min on ice. Chromatin was isolated after sonication to shear the DNA to an average length of 300–500 bp. Input and immunoprecipitated DNAs were treated with RNase, proteinase K, and heat for de-crosslinking, followed by ethanol precipi- tation. DNA libraries were prepared for sequencing using standard Illumina protocols