Possibly the most relevant and predictive cell line for in vitro potency assays was the A549-TMPRSS2 adenocarcinoma human alveolar basal epithelial cell line, whose receptors are closely related to respiratory cells; SARS-CoV-2 uses the SARS-CoV receptor ACE2 for host cell entry [64,65]. The gene discussed is TMPRSS2; the disease is adenocarcinoma.