PPL and central nervous system cancer: Multivariate Cox regression analysis showed that the expression of PCDH18 (p < 0.05), PPL (p < 0.05), DEPP1 (p < 0.01), VASN (p < 0.001), KCNE4 (p < 0.001), MYBPH (p < 0.001), C5AR2 (p < 0.001), and MARCH4 (p < 0.001) was an independent predictor of glioma which is most closely related to the survival of patients with glioma, independent of other variables, and has significant prognostic value (Figure 8).