This latter analysis revealed that Bcl-xS/Bcl-xL ratio was elevated after SF3B1 inhibition with pladienolide B in GBM in vivo (i.e., preclinical-xenograft GBM model) and GBM cells in vitro (U-87/U-118 MG cells and primary-GBM cell cultures) (Fig. 9h), but not in an available primary non-tumor cell cultures (Fig. 9i). The gene discussed is SF3B1; the disease is glioblastoma.