Thus, in a non-invasive mouse breast carcinoma cell line transfected with a constitutive active chicken c-Src mutant, a continual phosphorylation of Src at Tyr418 was shown, but it required Ca2+-dependent integrin-mediated cell adhesion to phosphorylate the focal adhesion kinase (FAK) at Tyr577, as well as the interaction of c-Src with phospho-FAK. Here, PTK2 is linked to breast carcinoma.