Fig. 4. (A) Glands inhibited with rFGFR2b were rescued with FGF7 and FGF10, which increased the number of end buds. Glands were treated with 1.6 µg/ml of rFGFR2b, and increasing doses of FGFs were added. Glands cultured with rFGFR2b were rescued only by FGF7 (500 ng/ml) and FGF10 (1000 ng/ml), and not by FGF1 (500 ng/ml) and FGF3 (1000 ng/ml), by other ligands for FGFR2b, or by FGF2 (200 ng/ml) or BMP7 (200 ng/ml). (B) A combination of neutralizing antibodies to FGF1, FGF7 and FGF10 was required to significantly inhibit branching morphogenesis (ANOVA, ^**P<0.01). Individual antibodies to FGFs (25 µg/ml), or combinations of either two or three antibodies or similar concentrations of either mouse or goat IgGs, were incubated with E12 SMGs for 48 hours. Individual anti-FGF antibodies or combinations of two anti-FGF antibodies (not shown) did not significantly inhibit branching. The number of buds was expressed as a ratio of the number of buds at 48 hours/number of buds at 2 hours (T48/T2).