Signal transducer and activator of transcription 3 (STAT3) is a transcription factor in the JAK/STAT signaling pathway that is activated by various cytokines and is involved in regulating processes such as the immune response, cell growth, differentiation, and survival. The STAT3 luciferase reporter vector is designed to study the transcriptional activity of STAT3. The vector contains a STAT3 DNA consensus binding site and TA minimal promoter upstream of a firefly luciferase reporter gene, which can specifically report STAT3 activity while maintaining a low basal level of transcription.