Interestingly, in lung cancer we noted a trend of down-regulations of MT2 with malignancy grade (G) in SCC types of analyzed tumors and no relation between MT1 and G. Recently, Nasrabadi et al. have shown the association between MT1 receptor mRNA levels and malignancy grade in patients over 50 years of age but they have not been able to observe any relationship between MT2 receptor expression and the clinico-pathological features of gastric tumor [43]. Here, MTNR1B is linked to lung cancer.