This clip from the MontanaPBS documentary, "Clearing the Smoke: The Science of Cannabis," shows how marijuana may cure some cancers.

From MontanaPBS: "CB2 Receptors act like a target for cannabinoids, and once they bind to the receptor, they tell the cancer cell to die. Because of this, cannabis can be used as an anti-cancer medicine."

"Clearing the Smoke" reveals how cannabis acts on the brain and in the body to treat nausea, pain and epilepsy, as well as cancer. Extensive interviews with patients, doctors, researchers and skeptics detail the promises and the limitations of medicinal marijuana.