The STAT5 Luciferase Reporter Lentivirus are replication incompetent, HIV-based, VSV-G pseudotyped lentiviral particles that are ready to be transduced into almost all types of mammalian cells, including primary and non-dividing cells. The particles contain a firefly luciferase gene under the control of STAT5-responsive element located upstream of the minimal TATA promoter. After transduction, activation of the STAT5 signaling pathway in the target cells can be monitored by measuring the luciferase activity.