evidence: In contrast to these positive effects, however, another early study on this topic reported that THC increases breast cancer growth and promotes tumour cell spread by inhibiting the antitumour immune response via enhancement of Th2-associated cytokines [138]. However, the study design used here was to exclude the direct growth inhibitory effect of cannabinoids on tumour cells in order to focus on the cannabinoid effect on the immune system. For this reason, tumour cells whose expression of cannabinoid receptors was low to undetectable were used in the experiments. This report was consistent with another, even earlier study that had observed tumour growth accelerating effects of THC based on reduced tumour immunogenicity [139]. A recent publication further reported that as a result of CB2 receptor-induced microglial M2 polarisation, conditioned media of cannabinoid-treated microglial cells increased rather than inhibited the angiogenic capacities of human brain microvascular endothelial cells [140]. The M2 polarisation induced by JWH-133 was demonstrated here by mRNA analyses showing increased levels of the M2 subtype markers CD206, arginase-1 (Arg1) and the chitinase-like protein Ym1 and decreased levels of the M1 subtype markers CD68, CD86 and inducible nitric oxide synthase (iNOS).