Fig. 6. PKC is required for cell spreading and FAK phosphorylation in 5-expressing and 5-deficient myoblasts. 5-expressing (5⁽⁺⁾) and 5-deficient (5^-/-) cells were plated on FN in the presence or absence of 3 nM PMA, , or PKC inhibitors (downward arrows), or PKC inhibitors in the presence of PMA (3 nM). FAK phosphorylation was determined after 30 minutes. The PKC inhibitor blocks FAK phosphorylation both in 5-expressing cells and in 5-deficient cells activated by PMA, whereas inhibitors of PKC and PKC had little effect. For the loading control, the level of FAK protein was determined by probing duplicate blots with an anti-FAK antibody.