Inhibition of ₂β₁ integrin expression by PD98059. Flow cytometric analysis of the ₂β₁ integrin expression by uninduced K562 cells, K562 cells induced for 6 days with PDB (40 nmol/L) (6d Ind), or K562 cells treated with PD98059 (50 μmol/L) for 15 minutes before the addition of PDB (40 nmol/L) (PD98059 + 6d Ind).