IP-MS assays were used to identify the protein(s) that might interact with ICAM3. Briefly, the THP1-Mφ stably expressing Flag-ICAM3 were co-cultured with WT authentic SARS-CoV-2-infected A549-ACE2 cells for 48 h. After co-culture, THP1-Mφ were lysed in NETN buffer and immunoprecipitated using anti-Flag M2 agarose (M8823; Sigma-Aldrich, MO, USA). After washing four times with the high stringent lysis buffer, the immunoprecipitants were resolved on gradient SDS-polyacrylamide gel electrophoresis (PAGE), and the gel bands were processed for mass spectrometry. Proteins were reduced with dithiothreitol, alkylated with iodoacetamide, and digested with trypsin. Peptides were extracted, vacuum-dried, and reconstituted in formic acid for MS analysis using an Orbitrap Fusion spectrometer. The tandem mass spectra were searched against the human UniProt database (version 20140922, containing 20,193 sequences) using MaxQuant (version 1.5.3.30). The false discovery rates (FDR) of the peptide-spectrum matches (PSMs) and proteins were set to less than 1%.