The majority of these CNS WHO grade 1 meningiomas (9/14, 64%) demonstrated minimal to absent p16 immunoreactivity (Supplementary Fig. 2 [Online Resource 2]), indicating a poor correlation between p16 expression and CDKN2A gene status in benign CNS WHO grade 1 meningiomas which we speculate is due to the low proliferation rate and cell cycle activity. This evidence concerns the gene CDKN2A and meningioma.