In one notable study in which 4-HPR treatment was used in combination with the knockdown of survivin, a prosurvival protein overexpressed in GBM that has been positively correlated with GBM cell proliferation, around 80% of the cells were apoptotic and in vivo angiogenesis studies showed a noticeable decrease in tumor vascularization [54, 56, 57]. Here, BIRC5 is linked to glioblastoma.