Figure 3. Active Akt prevents Grb7 upregulation in response to lapatinib.

A-D, SKBR3 cells were transduced with empty MSCV (vector), MSCVpuro-Akt S473D, or MSCVpuro-WT Akt. A, 2×10⁵ cells/well were plated in 6-well dishes, allowed to adhere for 24 h and subsequently used for cell lysates preparation. Phospho-Akt, total Akt and HER2 levels were detected by immunoblotting. B, 5×10³ cells/well were plated in 96-well plates, allowed to adhere and subsequently treated with lapatinib at the indicated concentrations. Viability was assessed 5 days later by colorimetric assay. C, D, 2×10⁵ cells/well were plated in 6-well dishes, allowed to adhere for 24 h and then incubated with or without 300 nM lapatinib (C, D) or 20 µM LY294002 for 24 h (D). Thereafter, total RNA was isolated and Grb7 (C) and Grb2 (D) mRNA levels were compared to those in vector cells. B-D Results are shown as means ± SD of three independent experiments. A, one representative experiment out of three is presented.