Ab109241

MSCs were lysed for SDS–PAGE. After electrophoresis, the denatured protein samples were transferred onto nitrocellulose membranes for incubation with primary antibody. Antibodies against PD-L1 (ab213524, Abcam, 1:1000 dilution), TP53 (2527 S, Cell Signaling Technology, 1:1000 dilution), P21 (ab109520, Abcam, 1:1000 dilution), GATA2 (ab109241, Abcam, 1:1000 dilution) and β-Actin (abs137975, Absin Bioscience Inc, 1:1000 dilution). After incubation with the primary antibodies overnight at 4 °C, the membranes were washed with TBST, followed by another incubation with HRP-conjugated secondary Goat Anti-Mouse IgG (H+L) antibody (115-035-003, AffiniPure, 1:1000 dilution) or Goat Anti-Rabbit IgG (H+L) antibody (111-035-003, AffiniPure, 1:1000 dilution) for 2 h at room temperature. The specific signals from the HRP-ECL reaction were visualized with a ChemiDoc imaging system (Bio-Rad). Relative quantification of protein bands from the Western blot images was performed with ImageJ software (version 1.52p).

ChIP assay was performed using the SimpleChIP Plus Enzymatic Chromatin IP Kit (#9005, Cell Signaling Technology). Chromatin was fragmented using the Bioruptor Pico sonication device (Diagenode). The fragmented chromatin was immunoprecipitated with either 3 μg antibody against GATA2 (ab109241, Abcam, 1:50 dilution) or nonspecific rabbit IgG as a negative control, at 4 °C for 12–16 h. Two primers were designed to detect GATA2 binding fragments at −153 bp (primer 1) and 93 bp (primer 2) of PD-L1. Primers for PD-L1 promoter binding site were listed in Supplementary Data 13.