This supplement provides detailed information on interferon receptor signaling pathways and their regulation of PD-L1 and PD-L2 expression. The study involves multiple cell lines and uses various techniques including reporter assays, ChIP, qPCR, and RNA-seq to analyze the molecular mechanisms underlying interferon signaling. Supplemental figures show the expression levels of interferon receptors, functional validation of reporter cell lines, and the effects of gene deletions on PD-L1 expression. Additional figures validate shRNA screen hits, compare ChIP results using different antibodies, and assess the effects of interferon on luciferase reporter constructs. The experimental methods describe the construction of promoter reporters, RNA-seq analysis, and gene set enrichment analysis. The study also includes lists of primers, immune cell markers, and references to relevant literature. The research highlights the role of interferon signaling in regulating PD-L1 and PD-L2 expression, which are important in immune evasion and cancer progression. The findings contribute to understanding the molecular mechanisms of immune checkpoint regulation and may have implications for the development of immunotherapies. The study provides a comprehensive analysis of the molecular pathways involved in interferon signaling and their impact on PD-L1 and PD-L2 expression.This supplement provides detailed information on interferon receptor signaling pathways and their regulation of PD-L1 and PD-L2 expression. The study involves multiple cell lines and uses various techniques including reporter assays, ChIP, qPCR, and RNA-seq to analyze the molecular mechanisms underlying interferon signaling. Supplemental figures show the expression levels of interferon receptors, functional validation of reporter cell lines, and the effects of gene deletions on PD-L1 expression. Additional figures validate shRNA screen hits, compare ChIP results using different antibodies, and assess the effects of interferon on luciferase reporter constructs. The experimental methods describe the construction of promoter reporters, RNA-seq analysis, and gene set enrichment analysis. The study also includes lists of primers, immune cell markers, and references to relevant literature. The research highlights the role of interferon signaling in regulating PD-L1 and PD-L2 expression, which are important in immune evasion and cancer progression. The findings contribute to understanding the molecular mechanisms of immune checkpoint regulation and may have implications for the development of immunotherapies. The study provides a comprehensive analysis of the molecular pathways involved in interferon signaling and their impact on PD-L1 and PD-L2 expression.