The relationship between lysate protein concentration from untreated and PDGF-treated NIH/3T3 cells and the absorbance at 450 nm using PathScan® Phospho-MEK1 (Ser217/221) Sandwich ELISA Antibody Pair #7211 is shown. NIH/3T3 cells were treated with PDGF for 20 minutes at 37ºC and then lysed.