TMPRSS2 and lung cancer: It is no coincidence that the murine homologue of TMPRSS2 is known as epitheliasin as the enzyme is broadly expressed in other epithelia, in particular on the lining epithelia of the aerodigestive tracts (lungs and colon), in kidneys, liver, and pancreas, in addition to several cancer cells including lung cancer cell lines A549 and Calu-3, and colorectal adenocarcinoma Caco-2 [58].