The CB2 receptors are mainly found on white blood cells, in the tonsils and in the spleen. The immune cells also express CB1, although there are fewer of them than CB2. In the immune system, one important function of the cannabinoid receptors is the regulation of cytokine release. Stimulation of the CB1 receptor produces marijuana-like effects on the psyche and circulation, while no such effect is seen when the CB2 receptor is activated. Therefore, selective CB2 receptor agonists have become increasingly popular subjects of research for their potential anti-inflammatory and anti-cancer effects.