This was identified in the human HL60 promyelocytic leukaemia cell line and has 44% homology to CB1.13 CB2 has been described in human immune cell subsets,8,11,12 particularly those of a myeloid lineage.14 Since the identification of CB1/2, other putative cannabinoid receptors have been identified, including GPR18,15 GPR55,16 GPR119,17 transient receptor potential channels,18,19 and peroxisome proliferator-activated receptors.19 This evidence concerns the gene CNR1 and acute promyelocytic leukemia.