Branching morphogenesis is one of the earliest events essential for the success of metazoans.

SPRY3 is a regulator of branching morphogenesis and is strongly expressed in Purkinje cells.

Here, we demonstrate that PTPRB negatively regulates branching morphogenesis in the mouse mammary epithelium.

Branching morphogenesis results in the formation of the conductive airway system, which is critical for alveolization.

Considering the importance of branching morphogenesis in multiple taxa, our findings have general importance outside mammary developmental biology.

Embryonic mammary gland development proceeds via placode, bud, bulb and sprout stages before the onset of branching morphogenesis.

In contrast, deletion of Wls in mesenchymal cells of the developing lung did not alter branching morphogenesis or early mesenchymal differentiation.

Mammary whole mount analysis revealed that Gas6 germline deletion does not impact ductal elongation, branching morphogenesis or terminal end bud formation.

Despite their distinct origins, morphologies and functions, different cell and tissue types use a remarkably conserved set of tools to undergo branching morphogenesis.

The mammary gland develops in a process known as branching morphogenesis, whereby a distal epithelial bud extends and bifurcates to form an extensive ductal network.

Culturing mouse fetal lung explants in the presence of recombinant human KGF also disrupted branching morphogenesis and resulted in similar cystic malformation of the lung.