Ligand for members of the frizzled family of seven transmembrane receptors. Functions in the canonical Wnt signaling pathway that results in activation of transcription factors of the TCF/LEF family (By similarity). Functions as upstream regulator of FGF10 expression. Plays an important role in embryonic lung development. May contribute to embryonic brain development by regulating the proliferation of dopaminergic precursors and neurons (By similarity). Palmitoleoylation is required for efficient binding to frizzled receptors. Depalmitoleoylation leads to Wnt signaling pathway inhibition. Belongs to the Wnt family.