SARS-CoV-2 and SARS-CoV Spike-Mediated Cell-Cell Fusion Differ in Their Requirements for Receptor Expression and Proteolytic Activation. - Hörnich BF; Großkopf AK; Schlagowski S; Tenbusch M; Kleine-Weber H; Neipel F; Stahl-Hennig C; Hahn AS (Journal of virology, 2021)