MCF-7, MCF-7-A2B1, and LCC9 (TAM-resistant (R)) cells were grown in SS medium for 48 h prior to treatment with vehicle control (DMSO), 100 nM or 1 μM 4-OHT, or 100 nM Fulvestrant for 4 days. A) Absorbance values are from one experiment in quadruplicate wells. *p < 0.05 one-way ANOVA, Tukey’s post hoc multiple comparisons test. B) Values were normalized to control within each cell line and are the mean ± SEM from 8 independent MTT assays. *p ≤ 0.01 and **p < 0.0001 two-way ANOVA, Bonferroni post hoc test. C) MCF-7-A2B1 cells were not transfected (C) or transfected with siControl (siCont) or siHNRNPA2B1 (siA2B1) in OPTI-MEM 48 h. Cells were grown in SS medium for an additional 24 h prior to isolation of WCE. The blot was stripped and re-probed for α-tubulin. The A2B1/α-tubulin ratios are shown. D) MCF-7-A2B1 cells were transfected with siControl (−) or siA2B1 for 48 h prior to counting and replating for 5 d MTT assays. Treatments: C = EtOH control, Fulv. = Fulvestrant. Values are the mean ± SEM from 6 experiments. **p < 0.0001 two-way ANOVA, Bonferroni post hoc test.