Parabens are known to bind to ERα (Routledge et al. 1998), promote a G1 to S-phase cell cycle progression, stimulate the proliferation of MCF-7 breast cancer cells (Darbre et al. 2003; Okubo et al. 2001; Wróbel and Gregoraszczuk 2013), and activate transcription of cell cycle (Wróbel and Gregoraszczuk 2014) and reporter genes (Darbre et al. 2003; Gomez et al. 2005). Here, ESR1 is linked to breast cancer.