Since ACE2 and TMPRSS2 expression is more abundant at basal condition (unstimulated condition) in Calu-3 than in MeT5A cells, we speculated that treatment with MS-275 acting on ACE2/TMPRSS2 expression may favor virus infection and replication in cells expressing at basal conditions low levels of receptors, thus favoring viral spreading to secondary sites of infection. Here, ACE2 is linked to infection.