Protection of HER2 downstream effectors FoxM1 and Akt. A. MDA‐MB‐435, SNCG stably transfected SNCG‐435‐3, SKBR3, and SNCG knockdown SKBR3/siSNCG cells were treated with 17‐AAG (1 μM) for 12 h. HER2, FoxM1, and actin expression were analyzed by Western blot. B. Protection of Akt activity. MCF‐7 and SNCG stably transfected MCFB6 cells were treated with 1 μM 17‐AAG or 1 μM Herceptin for 12‐h. Total proteins were subjected to Western analysis of Akt, phosphorylated Akt, and SNCG.