It was recently observed that tumor cells vary in terms of their apoptotic activity potential, and that alteration of the apoptotic machinery is a cause of chemoresistance and oncogenic transformation [48–49] By comparing gene expression of parental and secondary resistant cells, we observed in IB111 resistant cells a strong down-regulation of genes encoding for BH3-only factors such as BIM, BMF and PUMA. Here, BCL2L11 is linked to neoplasm.