Fig. 1

Quantitative analysis of TOP1 protein expression and TOP1 gene amplification across BC cell lines. a Western blot images. Blots were developed first with antibodies against TOP1 and then with anti-actin antibodies. BC cell line subtypes are indicated at the tops of the images. b The graph shows normalized data from (a). TOP1 protein levels in various BC cell lines were normalized to actin levels (see Methods). The arrows indicate TOP1 copy number in each cell line with amplification [46]. BC cell line subtype-based classification is indicated by bars and by colors: black – normal-like MCF10A cell line; yellow - Luminal subtype; blue - HER2 amplified, and orange - TNBC subtype. c Representative IHC images show TOP1 expression across BC cell lines. IHC sections (× 20 magnification) are placed in the same order as in a and b. For details, see magnified images (× 40) of nuclear TOP1 IHC staining of all BC cell lines analyzed in Additional file 1: Figure S1