Short-term effects of EGF and genistein on phosphorylation of the EGF receptor. Fibroblasts were cultured in the absence of EGF, which indicated the residual phosphorylation level (baseline value), and in the presence of EGF (100 ng/ml for 5 min) without any inhibitor (Ctrl) or with genistein (either 10 or 30 μM, marked as G10 or G30, respectively) or PD168393 (either 10 or 30 nM, marked as Inh10 or Inh30, respectively) added 30 min before EGF. Results of experiments with HDFa (wild-type), MPS II and MPS IIIB cell (fibroblast) lines are shown. Other tested fibroblasts gave similar results (results not shown). The results were calculated as phospho-EGF receptor fluorescence at 600 nm normalized to the total EGF receptor fluorescence at 450 nm. Therefore, the obtained normalized values are in arbitrary units. Values represent mean ± range of duplicate determinations.