Reporter cell lines are stable cell lines that carry reporter genes. A reporter gene is a gene encoding a protein or enzyme that can be detected, in other words, a gene whose expression can be easily identified. Reporter genes have been used to determine the activity of regulatory DNA sequences. When the regulatory sequences such as a promoter is under the control of a signaling pathway, the activation of the signaling pathway can be monitored by measuring the expression of reporter gene.

An ideal reporter cell line must meet the following requirements：

1.The reporter gene has been cloned into the cell and the sequence has been validated;

2.The reporter gene or its homolog does not exist in recipient cells. Therefore, the cell has no endogenous expression of the reporter gene;

3.The expression of the reporter gene can be quantitatively determined;

4.Most commonly used reporter genes include CAT ( chloramphenicol acetyltransferase), SEAP (secreted embryonic alkaline phosphatase), luciferase, etc.

5.CAT gene as a reporter gene can be detected by autoradiography.

Luciferase reporter gene has advantages including fast detection (no need for autoradiography), being more sensitive than the CAT method and low cost. SEAP can catalyze the phosphorylation of p-nitrophenol sodium to produce yellow light that can be detected at a wavelength of 405nm.

Reporter Cell line, as a method of tracking cellular signal transduction, has been widely used in the studies of gene expression regulation, signal transduction pathways and receptor-ligand interaction.