ChIP was performed with anti-HA-tag antibody (Abcam, ab9110) in MDA-MB-231 PD-L1 KO cells stably expressing HA-tagged PD-L1. For replicate 1, ChIP was performed using Diagenode iDeal ChIP-seq Kit for Transcription Factors (Diagenode, C01010055) with addition of ChIP cross-link Gold cross-lining reagent (C01019027). Library preparation and sequencing analysis were performed at the Molecular Biology Core facility in Dana-Farber Cancer institute. For replicate 2, ChIP was performed as described54 (link). Qualified libraries were deep sequenced using an Illumina HiSeq 4000 per the manufacturer’s instructions at the Northwestern University.