The focal adhesion is an important cellular structure that is involved in cell signaling, cell motility, and oncogenic transformation. Paxillin is a unique adapter protein that is localized to the focal adhesion and is involved in regulating various functions of the focal adhesion. The predicted amino acid structure for paxillin shows at the amino-terminus five LD motifs, a proline-rich domain, several potential phosphorylation sites and four carboxy-terminal LIM domains. Paxillin interacts with cell surface receptors and the actin cytoskeleton and activates several signal transduction pathways that are known to regulate normal cell physiology. Because paxillin is a central protein within the focal adhesion, it is a common target of many different oncoproteins, such as BCR/ABL, v-Src, and E6. In this review we summarize the current knowledge about the structure/function of paxillin and its family members, its role in integrin, cytokine signaling, and oncogenic transformation.