Then, membrane-bound serine(TMPRSS2)20 protease and CatL were foundto be involved in the hydrolysis of the scissile peptide bond of theS protein.21,22 Compelling evidence supportingthis theory is that a combination of inhibitors of both TMPRSS2 andCatL is under clinical trial as therapy against COVID-19 (the diseasecaused by SARS-CoV-2), at least ten of them showing favorable resultsin primary assays.18 This evidence concerns the gene TMPRSS2 and COVID-19.