ESR1 and atrial fibrillation: ESR1 expression was not altered in AF cells, but downregulated in NP cells after E2 or LMHFV treatments, both when compared to the control (0.13 ± 0.20- and 0.31 ± 0.06-fold for E2 and LMHFV, respectively, p < 0.05) and E2 + LMHFV (0.11 ± 1.6-fold for E2, p < 0.01, and 0.26 ± 0.56-fold for LMHFV, p = 0.067; Figure 2B).