Figure 4. Levels of different ACE2 isoforms and ACE2 enzymatic activity in cells or culture medium after spike protein, candesartan and captopril treatments.

Levels of ACE2 protein (A,D and E) and enzymatic activity (B and C) in cells (A and D) and culture medium (E) in cultures of human alveolar type-II A549 cells treated with spike protein alone or spike protein together with candesartan or captopril. Laser confocal microscopy showing colocalization (H, yellow) of ACE2 (green, F) and spike protein (red, G) in cells after treatment of cultures with spike protein. *P<0.05 relative to untreated controls; #P<0.05 relative to cells treated with spike alone (one-way ANOVA with Student–Newman–Keuls Method post hoc test or Kruskal–Wallis one-way analysis of variance on ranks with Student–Newman–Keuls method post hoc test); scale bar (for F–H): 25 µm.