Figure 3.

The difference in activation of estrogen receptor (ER)α and human epidermal growth factor receptor (HER)2 pathways between acquired-resistance cell rBT474 and BT474. (a) A comparison of rBT474 treated with 5 μM lapatinib and untreated BT474 cells; the expression of ERα, PR, and forkhead-box (FOX)O3a obviously increased. (b) The expression of phosphorylation of HER2 and protein kinase B (AKT) decreased in rBT474, but there was an increase in the expression of phosphorylation of extracellular-signal-related-kinase (ERK). (c) Increasing the expression of phosphorylation Src and caveolin-1 in rBT474 implied that the phosphorylation of Src activated the mitogen-activated protein kinase (MAPK)-ERK pathway, and then activated caveolin-1, which has the capacity to enhance the activation of transcription.