Involved in epithelial-mesenchymal interactions in kidney and lung morphogenesis that include epithelial differentiation and branching morphogenesis. May play a role in the specification or differentiation of one or more subsets of epicardial cell types (By similarity). Efficient DNA binding requires dimerization with another bHLH protein. Forms a heterodimer with TCF3 and binds the E box (5'-CANNTG-3') (By similarity).