XIAP and glioblastoma: Oleanolic and ursolic acid have also been shown to induce apoptosis and downregulate XIAP in hepatocellular carcinoma cells [47], while oleanolic acid decreased BIRC5 expression in human nonsmall cell lung cancer and ovarian cancer cells [27,59] and betulinic acid derivatives downregulated BIRC5 in glioblastoma cell lines [60].