To analyze whether these physiological levels of EGCG have any impact on breast cancer cell proliferation, we assessed doses of EGCG up to 1 μM in ERα-positive breast cancer cell lines, MCF7 (Figure 1A), T47D (Figure 1B), and an ERα-negative cell line MDA-MB-231 (Figure 1C). Here, ESR1 is linked to breast cancer.