Ubiquitous expression of EYFP or ECFP in R26R E8.5 embryos carrying a β-actin-Cre transgene. The two embryos, one carrying R26R-EYFP (right) and one carrying R26R-ECFP (left), were both heterozygous for the β-actin-Cre transgene. They are visualized with a YFP filter set (A), with bright field illumination (B), or with a CFP filter set (C).
Srinivas et al. BMC Developmental Biology 2001 1:4 doi:10.1186/1471-213X-1-4