These transgenic mice express the Tag-RFPT variant of Red Fluorescent Protein under the direction of the mouse Cited1, Cbp/p300-interacting transactivator with Glu/Asp-rich carboxy-terminal domain 1, promoter. TagRFP is the optimized monomeric derivative of the tetrameric eqFP578 from the sea anemone, Entacmaea quadricolor. RFP fluorescence is detected in the cap mesenchyme in the kidney and the male reproductive systems of hemizygous embryos, 15.5 embryonic days of age. Immunohistochemical analysis reveals that the TagRFP-T transgene is expressed in the expected Cited1 expression domain. Other possible sites of expression have not been characterized. Mice that are hemizygous for the knock in allele are viable, fertile, normal in size and do not display physical or behavioral abnormalities.This strain was transferred from the collection of the GenitoUrinary Development Molecular Anatomy Project (GUDMAP). The Jackson Laboratory 2024, used with permission.