a and 1b Effects of fibronectin and ascorbic acid on (top left) runx2 and (bottom left) osterix gene expression during the proliferative stage of osteoblast development on Ti-6Al-4V, as measured by quantitative RT-PCR. Changes in the relative levels of runx2 and osterix mRNA over time measured by quantitative RT-PCR are presented as relative levels of expression compared to control levels measured at day 0. Right column: Fold increase measured at day 10; data represent means ± SE. *Significantly greater than control or FN + AA groups at day 10 (P < .05) based on one-way ANOVA. Control and FN = disks were uncoated or precoated with 1 nmol/L fibronectin overnight, respectively, and plated with MC3T3 cells grown in culture media without ascorbic acid supplementation; AA and FN + AA = disks were uncoated or precoated with 1 nmol/L fibronectin overnight, respectively, and plated with cells grown in culture media supplemented with 100 μg/mL ascorbic acid with every media change.