A Representative images of organoids derived from MCF7-WT, MCF7-RBdel, T47D-WT, and RB-del cells that were treated with birinapant in combination with alisertib and CHIR124 at indicated concentrations for 6 days. B The viability of the organoids were determined by CTG assay. Graphs represent mean and SD from triplicates (*p < 0.05, **p < 0.01, ***p < 0.001 as determined student t-test). C Mice bearing MCF7-WT and RB-del xenografts were randomized for treatment with vehicle, Alisertib (10 mg/kg), birinapant (15 mg/kg) and the combination (Birina/Alis) for 3 weeks and the tumor growth was monitored regularly. Data show mean SEM (***p < 0.001 as determined two-way ANOVA). Box plots represent the tumor weights. Mean and SD are shown (*p < 0.05 as determined by 2-way ANOVA). D Western blot analysis on CIAP1 and cleaved PARP from the MCF7-WT and RB-del tumors at the end of treatment.