PLK1 and neurofibroma: Gene expression data were also available for 30 MPNST patient samples and eight benign neurofibromas (Kolberg et al., 2015), and in these patient samples, the gene expression of PLK1 was significantly upregulated in malignant tumors as compared to benign tumors (P = 0.004, two‐sided independent samples t‐test with equal variance; Fig. 4C, left panel).