ROSA26 is a locus used for constitutive, ubiquitous gene expression in mice.
[1] It was first isolated in 1991[2] by the group of Philippe Soriano in a gene-trap mutagenesis screen of embryonic stem cells (ESCs).
Over 800 knock-in lines have been created based on the ROSA26 locus according to the MGI database.
[3] The human homolog of the ROSA26 locus has been identified.
[4] ROSA stands for Reverse Orientation Splice Acceptor, named after the lentivirus genetrap vector.