BMP4 and glioblastoma: Compared with LGG, secondary GBM arising from LGG [48] showed higher expression of PRDM1, BMP8B, ACVR1, LIF, STAT3, ITGB1, WNT5A, CXCR4, MYC but decreased expression of genes related to germ cell fate, including Nanos3, DND1, BMP2, BMP4, SOX17, DDX4, SYCP3, DMC1 and ZP3 (Fig. 3A, C, and Additional file 1: Fig. S4A, Table S4), indicating that the PGC-EGC/ES-like conversion pathway rather than the mature development pathway might be activated in secondary GBM and that the activation of PGC-EGC/ES-like cycle was linked to the malignant prognosis of LGG.