Cytoskeletal protein involved in actin-membrane attachment at sites of cell adhesion to the extracellular matrix (focal adhesion). Binds in vitro to vinculin as well as to the SH3 domain of c-SRC and, when tyrosine phosphorylated, to the SH2 domain of v-CRK. Interacts (via LD motif 4) with PARVA/PARVIN and ILK. Phosphorylated on tyrosine residues during integrin-mediated cell adhesion, embryonic development, fibroblast transformation and following stimulation of cells by mitogens.