Cytoskeletal protein involved in actin-membrane attachment at sites of cell adhesion to the extracellular matrix (focal adhesion). Interacts in vitro with VCL/vinculin as well as to the SH3 domain of SRC and, when tyrosine phosphorylated, to the SH2 domain of CRK (By similarity). Interacts with GIT1 (By similarity). Interacts with NUDT16L1/SDOS (By similarity). Interacts with PTK2/FAK1 (By similarity). Interacts with PTK2B/PYK2 (By similarity). Interacts with ASAP2 (By similarity). Interacts with unphosphorylated ITGA4 (By similarity). Interacts with RNF5 (By similarity). Interacts with PDCD10 (By similarity). Interacts with NEK3, the interaction is prolactin-dependent (By similarity). Interacts with PTK6 (By similarity). Interacts with TGFB1I1 (PubMed:16546139). Interacts with SORBS1 (By similarity). Interacts with PARVB (By similarity). Interacts (via LD motif 4) with PARVA/PARVIN (PubMed:11134073). Interacts (via LD motif 4) with ILK (By similarity). Interacts (via cytoplasmic domain) with CEACAM1; the interaction is phosphotyrosyl-dependent (By similarity). Interacts with LIMA1; this complex stabilizes actin dynamics (By similarity). Interacts with CD36 (via C-terminus) (By similarity). Colocalizes with integrins at the cell periphery. Colocalizes with PXN to membrane ruffles and the leading edge of migrating cells (By similarity). Phosphorylated by MAPK1/ERK2 (By similarity). Phosphorylated on tyrosine residues during integrin-mediated cell adhesion, embryonic development, fibroblast transformation and following stimulation of cells by mitogens. Phosphorylation at Ser-273 by CDK5 reduces its interaction with PTK2/FAK1 in matrix-cell focal adhesions (MCFA) during oligodendrocytes (OLs) differentiation (By similarity). Phosphorylation at Tyr-31 and Tyr-118 by PTK6 promote the activation of RAC1 via CRK/CrKII, thereby promoting migration and invasion (By similarity). Phosphorylation at Ser-279 by SLK is required for PXN redistribution and cell motility (By similarity). Belongs to the paxillin family.