CD274 and neoplasm: Cho et al. [43] likewise investigated PD-L1 expression by immunohistochemistry using the same antibody (clone 22C3) and a similar interpretation protocol (PD-L1) positivity was defined by membranous PD-L1 staining in ≥ 1% of tumor and associated inflammatory cells or positive staining of stroma; PD-L1 expression was classified as high if at least 50% of the tumor cells, inflammatory cells, or stroma cells stained positive while PD-L1 expression in 0% to 49% of cells was classified as low expression).