Cellecta’s original CloneTracker™ 50M Lentiviral Barcode Library (formerly CellTracker) enables the tracking of individual clones derived from a population of cells. The library contains more than 50 million lentiviral constructs with different barcode sequences. When a cell population is transduced with this barcode library, the barcodes integrate into the genomic DNA of the cells. The result is a select starter founder population where almost every cell has a different, heritable, DNA-sequenceable barcode. Since the barcode is stably integrated, it is passed onto any cell progeny when genomic DNA is replicated, allowing researchers to track cell proliferation over the course of an experiment.