This protein catalyzes the final step in a branch of phenylpropanoid synthesis specific for production of lignin monomers. It acts on coniferyl-, sinapyl-, 4-coumaryl- and cinnamyl-alcohol. (E)-cinnamyl alcohol + NADP(+) = (E)-cinnamaldehyde + H(+) + NADPH Binds 2 Zn(2+) ions per subunit. Aromatic compound metabolism; phenylpropanoid biosynthesis. Homodimer. Most actively expressed in stem, hypocotyl and root tissue. Belongs to the zinc-containing alcohol dehydrogenase family.