Cyclin E2, but not cyclin E1, co-localises with NPAT by immunofluorescence in breast cancer cells. A. Cyclin E2 localises to NPAT foci. Confocal images of T-47D cells immunoprobed with cyclin E1 or cyclin E2 (red) and NPAT (green). Experiments performed in triplicate. Example of lack of co-localisation of cyclin E1 (antibody: HE12) and NPAT (antibody: C-19) is shown, and is representative of similar data with cyclin E1 (antibody: Epitomics) and NPAT (antibody: 27) co-staining (not shown). Scale bars = 5μm. Similar data obtained in MCF-7 cells are shown in Additional file 3. B. Confocal images of T-47D cells treated with 20nM cyclin E2 siRNA for 48h, and then immunoprobed with cyclin E1 or cyclin E2 (red) and NPAT (green). Scale bars = 10μm. C. Quantitation of co-localisation using Pearson's correlation coefficient (PCC) which quantifies positional relationship from confocal images on a scale of -1 to +1. Statistical significance was calculated with one-way ANOVA and Tukey’s multiple comparisons, where N.S. indicates not significant and ** indicates P < 0.01. Data pooled from duplicate experiments. Similar data obtained in MCF-7 cells are shown in Additional file 3.