PDCD1 and cancer: There was a trend towards a positive correlation between PD-1 mRNA and PD-1 expression in cancer cells (p = 0.082, Mann-Whitney), however not between PD-1 mRNA and PD-L1 expression in cancer cells or between PD-L1 mRNA and PD-1/PD-L1 expression in cancer cells (p > 0.1 each).