biostudies-literatureLu PNICHD NIH HHSNIEHS NIH HHSNHLBI NIH HHSNCI NIH HHS77-87https://www.ebi.ac.uk/biostudies/studies/S-EPMC2582391biostudies-literatureUnknown321(1)FGF signaling is associated with breast cancer and is required for mammary placode formation in the mouse. In this study, we employed a genetic mosaic analysis based on Cre-mediated recombination to investigate FGF receptor 2 (Fgfr2) function in the postnatal mammary gland. Mosaic inactivation of Fgfr2 by the MMTV-Cre transgene enabled us to compare the behavior of Fgfr2 null and Fgfr2 heterozygous cells in the same gland. Fgfr2 null cells were at a competitive disadvantage to their Fgfr2 heterozygous neighbors in the highly proliferative terminal end buds (TEBs) at the invasion front, owing to a negative effect of loss of Fgfr2 function on cell proliferation. However, Fgfr2 null cells were tolerated in mature ducts. In these genetic mosaic mammary glands, the epithelial network is apparenDevelopmental biologyGenetic mosaic analysis reveals FGF receptor 2 function in terminal end buds during mammary gland branching morphogenesis.PMC2582391CA057621U01 ES012801HD025331HL07731R01 CA057621R37 HD025331-20T32 HL007731-09T32 HL007731R01 CA057621-14R37 HD025331ES012801U01 ES012801-05Werb ZMartin GRLu PEwald AJfalseGenetic mosaic analysis reveals FGF receptor 2 function in terminal end buds during mammary gland branching morphogenesis.FGF signaling is associated with breast cancer and is required for mammary placode formation in the mouse. In this study, we employed a genetic mosaic analysis based on Cre-mediated recombination to investigate FGF receptor 2 (Fgfr2) function in the postnatal mammary gland. Mosaic inactivation of Fgfr2 by the MMTV-Cre transgene enabled us to compare the behavior of Fgfr2 null and Fgfr2 heterozygous cells in the same gland. Fgfr2 null cells were at a competitive disadvantage to their Fgfr2 heterozygous neighbors in the highly proliferative terminal end buds (TEBs) at the invasion front, owing to a negative effect of loss of Fgfr2 function on cell proliferation. However, Fgfr2 null cells were tolerated in mature ducts. In these genetic mosaic mammary glands, the epithelial network is apparen2008-01-01T00:00:00Z2008 Sep2025-04-20T02:07:43.355Z2019-03-27T00:19:20ZS-EPMC25823911858537510.1016/j.ydbio.2008.06.005