For example, Src can be recruited to Paxillin upon FAK phosphorylation; once Src is recruited, it phosphorylates other FAK tyrosine residues, such as Y925, increasing FAK activity and forming a FAK-Src complex (Figure 3.2) that phosphorylates adapter proteins, such as p130Cas, resulting in activation of Rac1 and increased cell motility in fibroblasts and epithelial cells (breast cancer) (Harte et al., 1996; Sawada et al., 2006; Zhou et al., 2021). This evidence concerns the gene PTK2 and breast cancer.