EIF2AK3 and type 1 diabetes mellitus: To assess whether increased PD-L1 levels after PERK inhibition mediate protection against T1D development, we treated female NOD mice that received HC-5770 for 2 weeks (6 to 8 weeks of age) with a single dose of monoclonal antibody against PD-L1 or the corresponding isotype IgG control, then continued HC-5770 treatment for an additional 2 weeks.