Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2022 May 18;203:105342. doi: 10.1016/j.antiviral.2022.105342

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

© 2022 The Author(s)

Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

PMC Copyright notice

Fig. 1 — U87 cells have no detectable endogenous ACE2 expression but high levels of Cathepsin B. A) Different cell lines were analyzed for ACE2 expression by immunoblotting, with β-actin as loading control. B) Same as in (A) but with the stably ACE2 transduced U87 cells, tested at an early (# 1) or late (# 32) passage of the cells. The transduced U87 cells stably express ACE2 at a very high level as compared to endogenous ACE2 in the Vero E6 cells. The same immunoblot is used for panel A and B, but with a longer exposure time for panel A in order to visualize the faint band in the Calu-3 sample. C) Comparative qPCR analysis of TMPRSS2 mRNA levels in different cells. Graph shows individual copy numbers/μl of 3 technical replicates (n = 3) as calculated from a TMPRSS2 standard. The TMPRSS2 level in Vero E6 cells was below detection limit. D) Different cell lines were analyzed for Cathepsin L (CTSL; left) and Cathepsin B (CTSB; right) expression by immunoblotting, with clathrin as loading control. For CTSL, different species are detected (indicated by the bracket): Pro-CTSL (41 kDa), glycosylated mature CTSL (31 kDa) and non-glycosylated mature CTSL (25 kDa), whereas only the Pro-CTSB form (42 kDa) is visualized. M: molecular marker in kDa, UD: undetectable.