Stable cell lines are a type of cultured cells that have been genetically modified to permanently express a particular gene of interest. These cells are usually generated by introducing a DNA construct, such as a plasmid or a viral vector, containing the gene of interest into the cells, followed by a selection process that allows the identification of cells that have integrated the DNA construct into their genome and are stably expressing the gene.

This cell lines have several advantages over transiently transfected cells, which express the gene of interest only for a short period of time. They provide a continuous source of cells expressing the gene of interest, which is important for many applications in biotechnology and biomedical research. In addition, stable cell lines can be used to study the effects of gene expression over longer periods of time, which can be important for understanding the regulation and function of genes in complex biological processes.

These cell lines are widely used in many areas of research, including drug discovery, gene therapy, and functional genomics. For example, stable cell lines can be used to screen large numbers of compounds for their effects on a specific gene or pathway, or to produce therapeutic proteins for use in biopharmaceuticals. Overall, stable cell lines are a powerful tool for studying gene expression and function, and are an important part of modern biological research.