ACE2 and small cell lung carcinoma: A daily pattern in ACE2 mRNA expression in rat lungs has not been investigated previously; however, our data are in accordance with datasets available for mice [45, 46], baboons [39] and humans [45] as well as the observation that ACE2 mRNA expression measured in a non-small-cell lung cancer cell line under in vitro conditions did not show a rhythmic pattern [3].