CD274 and pachyonychia congenita: In the other articles, the readers will find further information about PD-L1 IHC expression in PC patients (including discussion of pre-analytical and interpretation variables; correlation with clinic-pathologic features, the status of mismatch repair system, BRCA, PTEN and other main genes; results of clinical trials) and regulation of PD-L1 expression in pre-clinical PC models (intracellular signaling pathways, role in tumor microenvironment; experimental treatments on PC cell lines or mice; genetic and epigenetic regulation) [245,246,247,248,249].