ACE2 and COVID-19: The apparent lack of ACE2 expression in mouse cardiomyocytes, which contrasts with ACE2 being expressed in human cardiomyocytes and in cardiomyocytes derived from human pluripotent cells (Chen et al., 2020; Muus et al., 2021; Nicin et al., 2020; for review see Yiangou et al., 2021), underscores that there may be differences between human and mice regarding ACE2 expression, a notion that should be kept in mind when interpreting COVID-19 mouse experiments and translating data to the human situation.