The function of ICAM4 (intercellular adhesion molecule 4 (Landsteiner-Wiener blood group), Ensembl gene identifier ENSG00000105371) is as follows. Functions as a receptor ligand for the monocyte/macrophage- specific ITGAX:ITGB2 integrin complex and mediates erythrophagocytosis (PubMed:16985175). Receptor ligand of the platelet-specific ITGA2B:ITGB3 integrin complex involved in heterotypic cell-cell adhesion between erythrocytes and activated platelets (PubMed:12477717, PubMed:15355350). In vitro, is also a receptor ligand of multiple integrin receptors complexes such ITGAL:ITGB2, ITGAM:ITGB2, ITGA5:ITGB1, ITGA5:ITGB3 and ITGA5:ITGB5 integrin complexes (PubMed:10846180, PubMed:11435317, PubMed:15355350). {ECO:0000269|PubMed:10846180, ECO:0000269|PubMed:11435317, ECO:0000269|PubMed:12477717, ECO:0000269|PubMed:15355350, ECO:0000269|PubMed:16985175}.