FIGURE 5.

Raf isoforms are essential for phosphate-induced ERK1/2 phosphorylation. Hypertrophic chondrocytes were incubated with 7 mm sodium sulfate (−) or sodium phosphate (+) for 30 min prior to Western analysis of whole cell extracts for phosphorylated (P) and total ERK1/2. Data are representative of three independent chondrocyte preparations per genotype. The graph shows the ratio of pERK1/2 signal in the Western blots of phosphate- versus sulfate-treated chondrocytes, normalized for total ERK1/2 in the same sample, as quantitated by ImageJ64 software. *, p = 0.0012 versus control.