Figure 4

Prospective mediators of epithelial-mesenchymal interactions identified by network analysis. (A) List of likely effectors of inductive signalling across the mesenchymal-epithelial boundary. In addition to ligand-receptor pairs, inter-connections between known signalling cascade components that could transmit signals across the mammary mesenchyme (MM) and the mammary bud epithelium (MBE) and vice versa are shown. (B) Mesenchymal Decorin (Dcn) is poised to interact with both epithelial CollagenIVa5 and CollagenIVa6 (Col4a5 and Col4a6). Red represents mesenchymal nodes. Green represents epithelial nodes. (C, D) Decorin and CollagenIV expression patterns suggest that these interconnected nodes represent feasible biological interactions that could modulate signals both within the extracellular matrix and basement membrane and across the mesenchymal-epithelial boundary. Scale bar is 50 μm.