FKBP4 and glioblastoma: In conclusion, FKBP51 plays a dual role in glioma dynamics: its spliced isoform, FKBP51s, promotes malignancy by enhancing anti-apoptotic capacity in GBM stem-like cells, whereas the full-length FKBP51 (isoform 1) can inhibit tumor growth by suppressing proliferation and inducing apoptosis through AKT pathway modulation.