Figure 3.

Letrozole and AEW541 both modulate IGF-IR pathway signaling via the PI3K/PKB axis. (a) Steroid-deprived MCF7/Aro cells were treated for 24 hours with either no androstenedione (Δ4A; lane 1), Δ4A in the presence of dimethyl sulfoxide (DMSO; lane 2), or Δ4A in the presence of 92 nmol/l AEW541 (lane 3) or 445 nmol/l letrozole (lane 4), or both combined (lane 5). Cells were processed for Western blotting with specific antibodies for the proteins indicated. Note that samples were processed in parallel to fluoresence-activated cell sorting (FACS) data shown in Figure 2. (b) Steroid-deprived MCF7/Aro cells were treated for 96 hours with either no Δ4A (lane 11), Δ4A in the presence of DMSO (lane 1), or Δ4A in the presence of 33, 55, and 92 nmol/l AEW541 (lanes 2 to 4), 158, 265 and 445 nmol/l letrozole (lanes 5 to 7), or both respectively combined (lanes 8 to 10). Cells were processed for Western blotting with specific antibodies for the proteins indicated. Note that samples were processed in parallel to FACS data displayed in Figure 4. *Background band. Casp, caspase; IGF-IR, insulin-like growth factor I receptor; IRS, insulin receptor substrate; MAPK, mitogen-activated protein kinase; PARP, poly [ADP-ribose] polymerase; PKB, protein kinase B.