Schematic diagram of selected Ig-superfamily members bearing one or more ITIMs (adapted from ref. 48). See Table 2 for a complete list of Ig-ITIM family members that bind SHP-1, SHP-2, or both, as well as the detailed amino acid sequence separating the paired ITIMs. Ig, immunoglobulin; ILT, Ig-like transcript; ITIM, immunoreceptor tyrosine–based inhibitory motif; KIR, killer inhibitory receptor; PECAM-1, platelet endothelial cell adhesion molecule-1; PIR-B, paired Ig-like receptor-braking protein; SIRP, signal regulatory protein.