PIAS1 and infection: We found that those CRISPR-targeted cells with decreased ACE2 expression (SMAD4, EP300, and PIAS1) also exhibited a decrease in both the proportion of infected cells by SARS-CoV-2 nucleocapsid protein immunofluorescence (Fig 5A) and in viral infectivity by TCID50 (Fig 5B) at 48 hours post-infection.