IFN-γ strongly increased PD-L1 and β2-microglobulin expression on RT2-cancer cells but not on RT2.Stat1−/−-cancer cells; β2-microglobulin+ cells were found in sections of RT2.Stat1−/−-cancers, showing that IFN-γ-responsive host immune cells infiltrated the tumour microenvironment during ICB (Supplementary Fig. 4a–d). This evidence concerns the gene STAT1 and cancer.