Syncytium formation was observed in VeroE6/TMPRSS2, Rc, and iMylc-D05-s-ML2 cells by 48 hpi (Figure 4A), but not in BHK cells, human lung cancer-derived Calu-3 cells, or porcine kidney-derived PK-15 cells (Supporting Information: Figure S2). Here, TMPRSS2 is linked to lung cancer.