HTR4 and central nervous system cancer: The aim of this study was to analyze the protein-expression profile of <i>HTR4</i> and <i>PDE4D</i> genes in patients with glioma by immunohistochemical (IHC) analysis, to determine whether some interrelationship between them exists, to correlate their expression with clinical and histopathological parameters and therapy, and to determine their impact on patients' survival.