Fig. 4

Activation of signal transduction proteins by IGF-1 in oestrogen-responsive breast cancer cells. MCF-7, ZR-75 and EFM-19 cells were cultured for two days in phenol red-free medium supplemented with charcoal-treated serum, for 2 h in serum-free medium and incubated in the absence or presence of the indicated concentrations of IGF-1 for 15 min in the same medium. Aliquots of 10 μg of protein were electrophoresed on polyacrylamide gels, transferred to nitrocellulose and incubated with antibodies specific for phosphorylated IGF receptor, phosphorylated IRS-1, phosphorylated Akt, phosphorylated Bad, and phosphorylated ERK1 and ERK2, antibodies against the equivalent total proteins and developed as described in the Materials and Methods. Representative images from the phosphorylated protein are shown above those of the equivalent total protein