FN1 and breast neoplasm: Indeed, a CK II consensus site on NMIIA (S1943) is highly phosphorylated in breast tumor cells during cell spreading and integrin-fibronectin engagement45; however, neither pharmacological nor siRNA KD of different CK II subunits significantly reduces S1943 phosphorylation, indicating that the CK II is probably not the bona fide kinase that regulates NMIIA S1943 phosphorylation in vivo.