(biochemistry) The α (alpha) component of various integrins, especially ones in which the β (beta) component is CD18 (i.e. β2) and which mediate leukocyte adhesion.

a protein part of lymphocyte function-associated antigen 1 and so involved in cellular adhesion and costimulatory signaling in the human immune system.

the alpha protein subunit that forms with CD18 the heterodimeric integrin macrophage-1 antigen (Mac-1) also known as complement receptor 3 (CR3), present on the surface of many leukocytes involved in the innate immune system

a receptor tyrosine kinase protein, cytokine receptor and proto-oncogene