TMPRSS2 and viral infectious disease: In this process, PCIF1 exerts its antiviral function by affecting ETS1 stability by installing m6Am. On the other hand, in SARS-CoV-2 infection, PCIF1 maintains the stability of angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2) mRNA by installing m6Am, promoting their expression and facilitating viral infection (240).