For determination of the PSGL-1 expression on circulating monocytes, 5 additional consecutive patients (3 female, 2 male, mean age 66 years, range from 48 to 86 years) with newly diagnosed GBM- and 5 age- and gender matched healthy controls (3 female, 2 male, mean age 67 years, range from 54 to 84 years) were enrolled in the study. Here, SELPLG is linked to glioblastoma.