Western Blot Analysis of ACE2 Protein

We performed western blot analyses, as described previously [29 (link)]. In this context, we briefly lysed the cells in lysis buffer (20 mM HEPES, pH 7.5, 150 mM NaCl, 1% (v/v) Triton X-100, 10% (v/v) glycerol, 1 mM EDTA, 50 mM NaF, 50 mM β-glycerophosphate, 1 mM Na₃VO₄, and 25 μg/mL each of antipain, leupeptin, and pepstatin) for 30 min on ice. After centrifugation at 20,400 g for 10 min at 4°C, we collected the lysates, separated them by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, transferred them onto polyvinylidene difluoride membranes (Merck KGaA, Darmstadt, Germany), and analyzed them by Western blotting. We measured protein levels using the following primary antibodies: anti-ACE2 antibody (ab273433, 1:1000; Abcam, Cambridge, UK) and anti-β-tubulin antibody (#5346, 1:1000; Cell Signaling Technology, Danvers, MA, USA).