Table 1.

Signaling molecules localized to mammary buds

Epithelium	Mesenchyme
PTHrP	PTH1R
Wnts 10a, 10b, 6	Eda-A1
β-Catenin	Wnt11, Wnt5a
Axin2	Lef1
Lef1	β-Catenin
Kremen 2	Fgf7
FGFR2b, FGFR1b	MSX2
Fgfs 4,8,9,17	TBX2
Sonic Hedgehog, Indian Hedgehog	Hoxa9, Hoxb9, Hoxc9
Gli2, Gli3, Ptc1	BMP4
BMP2	ER-α, ER-β
Edar	Androgen receptor
MSX1, MSX2	Pdgfr
Irx2	Tenascin C
Lmx1b
TBX3
PdgfA

Edar, ectodysplasin receptor; FGF, fibroblast growth factor; Lef, lymphoid enhancing factor; Pdgfr, platelet-derived growth factor receptor; PTH1R, PTHrP receptor 1; PTHrP, parathyroid hormone related protein