FIG. 4.

Fluid flow shear stress increases mRNA for E11 in MLO-Y4 cells and mineralizing 2T3 cells. Northern blotting of E11 mRNA in MLO-Y4 cells after exposure to fluid flow shear stress at 4 and 16 dynes/cm² showed a twofold increase at 2 h after shear stress but not at 24 h, indicating that E11 is an early-response gene. The data represent an average of two experiments as shown on the graph. E11 is also an early-response gene in mineralizing 2T3 cells, as shown by an increase at 2 h after exposure to fluid flow shear stress at 16 dynes/cm², compared to OPN (osteopontin), which is a late-responding gene increased at 24 h, not at 2 h, after shear stress. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.