Fig. 1

Mammary gland phenotype of AF-1⁰ and AF-2⁰ mice. a Schematic representation of the mutant genomic loci and the ERα proteins expressed in WT mice, AF-1⁰ mice with deletion of amino acids 2–148, and AF-2⁰ mice with deletion of amino acids 543–549. Only the main protein initiated by the translational initiation codon in exon 1 on amino acid 1 (ATG) is shown for each genotype. The less abundantly expressed protein is initiated in exon 2 on amino acid 178. b Whole-mount stereomicrographs of inguinal mammary glands from 7-week-old WT, AF-1⁰ and AF-2⁰ females. Arrowheads indicate TEBs. Black lines mark the borders of the ductal outgrowth. Scale bars: 5 mm (left), 2 mm (right). LN sub-iliac lymph node. c Dot plot showing extent of fat pad area filled by the engrafted WT, AF-1⁰ and AF-2⁰ epithelia at different developmental stages (n = 3–18). Shown are means ± SEM; unpaired, two-tailed, Student’s t test, ^*p < 0.05, ^**p < 0.01, ^***p < 0.001, ^****p < 0.0001, n.s. not significant. d ERα IHC of mammary glands from 3-week-old WT, AF-1⁰, AF-2⁰ and ERα^−/− mice. Representative pictures of glands analysed from three females of each genotype are shown. Scale bar: 100 μm