Unlike tumors that have been treated with blank MPs, treatment of U87-derived xenografts with THC- or CBD-loaded MPs or with a mixture of THC and CBD MPs reduced cancer cell proliferation (as determined by Ki67 immunostaing, Figure 4A), enhanced apoptosis (as determined by TUNEL; Figure 4B) and decreased tumour vascularization (as determined by immunostaining with the endothelial cell marker CD31, Figure 4C). This evidence concerns the gene MKI67 and cancer.