Kim and colleagues [53] found that there was a difference between CSF composition of patients with meningioma and patient-control population in eleven different protein expression: serum albumin precursor, apolipoprotein E (Apo E), apolipoprotein J precursor (Apo J), transthyretin precursor (TTR), prostaglandin D2 synthase (PTGDS), proapolipoprotein, chain D hemoglobin ypsilanti, alpha-1-antitrypsin (AAT), and beta-2-microglobulin precursor (b2M). Here, B2M is linked to meningioma.