Each vial contains a stable population of MCF7 cells expressing the NucLight Red fluorescent protein restricted to the nucleus. Parental MCF7 cells were purchased from ATCC (Cat# HTB-22). MCF7 cells were transduced with the Incucyte® NucLight Red Lentivirus (Cat# 4476; EF1α, puromycin) at an MOI of 3 (TU/cell) in the presence of 8µg/ml polybrene following the standard Essen protocol. This resulted in ≥70% transduction efficiency. 48 hours post infection, the complete population of cells was grown for 3-5 days in complete growth media containing 1µg/ml Puromycin to select for cells expressing NucLight Red. NucLight Red expressing cells are maintained in complete media containing 0.5µg/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 (see below). In addition, all cells in our NucLight catalog have been certified mycoplasma free by ATCC and our stable populations have been unambiguously authenticated using ATCC’s Short Tandem Repeat (STR) profiling.