Disruption of overlapping transcripts in the ROSA βgeo 26 gene trap strain leads to widespread expression of β-galactosidase in mouse embryos and hematopoietic cells - Zambrowicz,B.P.; Imamoto,A.; Fiering,S.; Herzenberg,L.A.; Kerr,W.G.; Soriano,P. (Proc Natl Acad Sci USA, 1997)