MKI67 and glioblastoma: 15) in 2011. Authors demonstrated that regorafenib exerts a huge antiangiogenic effect and a dose-dependent tumour growth inhibition, characterised by significant reduction of tumour cells proliferative index, as addressed by immunostaining with KI67 antibody. The anticancer effectiveness of regorafenib on GBM was confirmed in xenograft models established in immunosuppressed mice upon injection of the GBM stable cell line U87 (Ref. 31).