CD274 and cancer: However, significant associations were found between NKAIN1 protein expression in cancer nests and CTLA-4 (r = 0.246, P < 0.001) as well as PD-L1 expression (r = 0.215, P < 0.001) within cancer nests, demonstrating statistical significance (see Figs. 2 and 3A and Table S1).