Figure 2

Crosstalk between the PI3K pathway and the MEK–ERK pathway. The MEK inhibitors PD98059 and UO126 abolish stimulation by IGF-1 of ERK phosphoryation but have no influence on the phosphorylation of Akt (first and third panel). The inhibitors of the PI3K pathway Wortmannin and Ly294002, on the other hand, inhibit the phosphorylation of Akt (PKB), confirming that Akt becomes phosphorylated through activation of the PI3K pathway (third panel), but also reduces the phosphorylation of ERK1 and 2 (first panel). The cells were stimulated with 100 ng ml⁻¹ IGF-1 for 10 min and lysates were treated as in the previous figure. One experiment representative of four is shown.