Additionally, the SERM actions of melatonin can be explained since breast cancer cells express the melatonin receptor type 1 (MT-1) located in the membrane (Figure 1); the binding of melatonin to the MT-1 receptor results in inhibition of adenylate cyclase, therefore decreasing cAMP intracellular levels [29]. The gene discussed is ADCY1; the disease is breast carcinoma.