Active ESR1 fusion proteins upregulate expression of estrogen response and EMT genes. A, Heatmap showing the differently expressed genes in the T47D RNA-seq data. B and C, Active ESR1 fusions upregulate expression of two clusters of estrogen response (early and late) and EMT-related genes as indicated. D and E, Expression of estrogen response genes (GREB1, TFF1, and PGR) and EMT-related genes (VCAN and SNAI1) was measured by RT-qPCR in E2-deprived T47D cells treated with vehicle (+DMSO) or 100 nmol/L fulvestrant (+Fulv) in the absence (–E2) or presence (+E2) of 10 nmol/L E2 for 48 hours. Values were normalized to GAPDH mRNA, and relative expression was calculated as fold change to YFP, –E2 (mean ± SEM; n = 3). One-way ANOVA followed by Dunnett multiple comparisons test was used to compare each E2-deprived T47D cell line with YFP control cells (*, P < 0.05; ***, P < 0.001; ****, P < 0.0001). Two-way ANOVA followed by Bonferroni test was used for multiple comparisons for each stable cell after 100 nmol/L fulvestrant treatment. F, Snail and E-cadherin proteins were measured by immunoblotting in E2-deprived cells treated with or without 100 nmol/L fulvestrant (Fulv). GAPDH protein served as a loading control. The dashed line indicates two separate blots that were conducted at the same time. The representative image is from three independent experiments.