ESR1 and breast cancer: Although both stimuli maintain high protein levels at 24 h of cell culturing (Figure 2H), the Western blot analysis of NGB in CM with respect to amphiregulin (AREG), a commonly released factor by ERα+ breast cancer cells [23], and the ELISA analysis of CM indicate that H2O2 greatly accumulates NGB in the extracellular milieu, while E2 triggers a significant reduction to the control (Figure 2I,J), indicating that the two NGB inducers exert opposite effects on NGB extracellular release.