The estrogen receptor (ER) is a nuclear hormone receptor that mediates the effects of estrogen and related hormones and regulates the expression of genes involved in processes such as cell proliferation, differentiation, reproductive health, bone metabolism, immune function, and cardiovascular health. The ER luciferase reporter vector is designed to study the transcriptional activity of this receptor. The vector contains an ER DNA consensus binding site and TA minimal promoter upstream of a firefly luciferase reporter gene, which can specifically report ER activity while maintaining a low basal level of transcription.