Combined treatment with gamitrinib and histone deacetylase (HDAC) inhibitors elicits synergistic reduction in cellular proliferation of glioblastoma (GBM) cells. (A,B) U87, LN229, GBM12 and GBM43 cells were treated with gamitrinib (GTPP), panobinostat (Pb)/romidepsin (Ro) or the combination of GTPP and panobinostat/romidepsin for 72h. Thereafter, cellular viability and statistical analysis were performed. Isobolograms are shown; (C,D) The graphs show cellular viability data following treatment with vehicle, panobinostat/romidepsin, gamitrinib or the combination for 72h in the indicated GBM cells (n = 3, 4). Shown are means and SD. ANOVA was used for statistical analysis. ** p < 0.01, ***/**** p < 0.001.