TPA is a potential tumor promotor and an activator of protein kinase C(PKC). TPA can activate PKC as a substituter of DG in a very low concentration, thus causing a serial of changes of cells’ function. Observing the change in adhesion of NIH3T3 cell after using 100 nmol/L TPA to act on NIH3T3 cell, it was discovered that TPA increase NIH3T3 cell adhesion to Fn by increasing synthesis of integrin α₅、β₁ subunits. Further study on the content of integrin α₅、β₁ subunits——the major receptor of Fn on the cells’ surface showed that after the TPA acts on cell for 24 hours, the content of integrin α₅、β₁ subunits increased 52.3% and 51.6% respectively. To analyze the total content of N-oligosaccharides and its constituent propertion after TPA acts on cell, ³H-mannose incorporation into N-oligosaccharides and lectins chromatography were used. The result has no difference from that of control. It can be said that increasing adhesion is induced increasing the syntheses the content of α₅ and β₁ subunits of the cells. The PKC inhibitor Sphingosine was added during TPA acting on cell, it was found that both the α₅ and β₁ content and the adhesion of cells to Fn recovered to the control level. It proved that increasing α₅β₁ synthesis thus increasing adhesion of cell to Fn by TPA is mediated by PKC. Besides the inhibitor of tyrosine protein kinase also can block the action of TPA increasing the content of α₅β₁ integrin syntheses.