These conflicting results may be attributed to several factors: differences in demographic and molecular characteristics among the patient cohort, differences in the underlying mechanisms of PD-L1 expression, differences in antibody clones and cutoff values used to determine PD-L1 positivity, differences in targets used to evaluate PD-L1 expression (whether or not PD-L1 expression on tumor-infiltrating immune cells was included), and differences in the condition of tissue fixation and stability of epitopes during immunohistochemistry (IHC) reactions. The gene discussed is CD274; the disease is neoplasm.