Figure 1
From: FTY720 in resistant human epidermal growth factor receptor 2-positive breast cancer
Characteristics of the five HER2-positive cell lines. (a) HER2 expression was confirmed through Western blot analysis in the five cell lines. Estrogen receptor expression was revealed in the BT-474 cell line compatible with its known feature. BT-474-HR1 cells derived from BT-474 cells retained estrogen receptor expression after selection from trastuzumab-resistant clones. (b) The growth inhibition status in the five cell lines was shown after treatment with different concentrations of trastuzumab. The percentage of WST-1 absorbance in the cells was determined 72 h after the incubation with trastuzumab (0.5–16 μg/mL) and then normalized to non-treated cells. Each plot indicates the mean value of at least three experiments, whereas error bars indicate the standard error of the mean. (c) The presence of PIK3CA gene mutation was evaluated in the three trastuzumab-resistant cell lines using direct exon 9 and 20 sequencing.
