a, qRT-PCR analysis of PD-L1 mRNA decay in H1944 cells expressing control or UROD sgRNA after treatment with 10 μM Actinomycin D in n=3 technical replicates per time point, across 4 time points. b, Quantification of PD-L1 levels, determined by western blot, in H1944 cells expressing control or UROD sgRNA after treatment with 20 μM cycloheximide across 5 time points. c, Immunoprecipitation of endogenous PD-L1 in H1944 cells transfected with control or UROD siRNA treated with 10 μM Velcade for 24 hours. Protein abundance and ubiquitylation monitored by western blot. Experiment in (c) was performed two independent times, with similar results. Data from a representative experiment are shown.