CDK4 and meningioma: erb-b2 receptor tyrosine kinase 2 (ERBB2), a member of the epidermal growth factor receptor family, along with genes such as cyclin dependent kinase 4 (CDK4), AKT serine/threonine kinase 3 (AKT3) and TP53 function inhibitor- murine double minute 2 (MDM2), are amplified and overexpressed in gliomas, glioblastoma and meningioma [63,64,65,66].