RPL17 and neoplasm: Lastly, PD1 expression on T-cells, measured by the PD1/CD4 ratio, was significantly higher in cases with tumor spread through air spaces (STAS) (p = 0.010), with values of 0.90 ± 0.17 in cases with STAS and 0.73 ± 0.41 in cases without STAS.