KLF4 and meningioma: A new finding of WHO 2021 classification is the inclusion of several molecular biomarkers associated with the classification and grading of meningiomas, e.g., SMARCE1 in clear cell subtype, BAP1 in rhabdoid and papillary subtypes, KLF4/TRAF7 in secretory subtype mutations, and TERT promoter mutation and/or homozygous deletion of CDKN2A/B in anaplastic meningiomas.