Similarly, targeted ablation in the mammary epithelium of focal adhesion kinase (FAK), a cytoplasmic tyrosine kinase and important mediator of Integrin signaling, significantly suppresses mammary carcinoma incidence in the mouse MMTV-PyVT model by affecting the pool of MaSC in the untransformed mammary gland and mammary cancer stem cells (MaCSC) in the primary tumors [19], [20]. Here, PTK2 is linked to breast cancer.