High-affinity G protein-coupled receptors MT1 (MTNR1A in humans) and MT2 (MTNR1B in humans) are found in various cellular locations, and through engagement with these receptors, melatonin can exert its effects on sleep and mood, learning and memory, and even cancer progression (Liu et al., 2016; Pistioli et al., 2021). This evidence concerns the gene MTNR1B and cancer.