SF3B1 and glioblastoma: Pladienolide B treatment also decreased the expression of key tumor progression markers and critical oncogenic spliceosome components [previously found to be correlated with SF3B1 in GBM samples (Fig. 1l-m)] in both cell lines (Fig. 5k and m, respectively) and primary-GBM cell cultures (Fig. 5l and n, respectively).