Figure 6. Amount of Hb-EGF released by irradiation is sufficient to induce the phosphorylation of ERKs.

(A) Serum-starved HeLa cells were irradiated with 875 MHz at an intensity of 0.344 mW/cm² for 5, 10 and 15 min. Hb-EGF was enriched using heparin and subjected to Western blot analysis using anti-Hb-EGF antibodies (αHb-EGF), together with known concentrations of Hb-EGF (100 and 200 pg). (B) Low concentrations of Hb-EGF (50, 100 and 200 pg/ml) were used to stimulate ERKs in serum-starved HeLa cells. After stimulation for 2–15 min, the cells were harvested and subjected to Western blot analysis with anti-pERK (α pERK) and anti-total ERK (α ERK) antibodies.