Among the identified differentially expressed proteins, 6 candidates; hemopexin, serum albumin, haptoglobin, alpha-2-macroglobulin, apolipoprotein A-I and serotransferrin were found to be commonly altered in grade I and grade II meningiomas, however levels of differential expression (fold-changes) was found to be different (Figure 2). This evidence concerns the gene HP and meningioma.