For 10 points, name these proteins that play a key role in cell adhesion by linking the cytoskeleton to the extracellular matrix.
One of these proteins deficient in patients with LAD1 pairs with another one used as a common histological marker for microglia to form the complement receptor macrophage-1 antigen. Osteopontin and bone sialoprotein are two of the five SIBLING proteins that bind to these proteins. Rap1 is a member of the Ras GTPase family that activates these proteins. Some of these proteins recognize and bind an LDV sequence, but more of them recognize an RGD motif. These proteins can engage in "inside-out" signaling, and participate in (*) heterophilic interactions, similar to selectins but unlike cadherins. These proteins act as transmembrane adhesion proteins for focal adhesions and hemidesmosomes. For 10 points, name these proteins that play a key role in cell adhesion by linking the cytoskeleton to the extracellular matrix. 
One of these proteins deficient in patients with LAD1 pairs with another one used as a common histological marker for microglia to form the complement receptor macrophage-1 antigen.
integrins