CDKN1B and glioblastoma: The two GBM models were differentiated by the presence or absence of CDKN1B (Model 1 (CDKN1B, T stage, N stage, histological grade, lymphovascular invasion, perineural invasion, ER and HER2) versus Model 2 (T stage, N stage, histological grade, lymphovascular invasion, perineural invasion, ER and HER2)).