PLK1 and glioblastoma: The expression levels of other PLK family members PLK3 (logFC = 0.92138804; P < 0.0001) and PLK4 (logFC = 0.40736722; P < 0.0001) was up-regulated in GBM (n = 276) compared with normal non-tumor tissues (n = 8) in Figs. 2C and 2D.