Each vial contains a stable population of 1 million MCF-7 cells expressing the Incucyte® Nuclight Red fluorescent protein restricted to the nucleus. Parental MCF-7 cells were purchased from ATCC (Cat. No. HTB-22). MCF-7 cells were transduced with the Incucyte® Nuclight Red Lentivirus (Cat. No. 4476; EF1α, puromycin) at an MOI of 3 (TU/cell) in the presence of 8 µg/ml polybrene following the standard infection protocol, resulting in a ≥70% transduction efficiency. 48 hours post infection, the complete population of cells was grown for 3-5 days in complete growth media containing 1 µg/ml puromycin to select for cells expressing Incucyte® Nuclight Red. Incucyte® Nuclight Red expressing cells are maintained in complete media containing 0.5 µg/ml puromycin. Following selection, a panel of validation assays designed to evaluate the effects of nuclear label expression on functional cell biology was completed. These assays include comparisons of cell morphology and growth/proliferation between stable populations and the parent populations from which they were derived. In addition, all cells in our Incucyte® Nuclight catalog have been certified mycoplasma free by ATCC.